Interstate 70
Interstate 70 (I-70) is a major east–west Interstate Highway in the United States that extends 2,153 miles (3,465 km) from its western terminus at an interchange with Interstate 15 near Cove Fort, Utah, to its eastern terminus near Baltimore, Maryland, at interchanges with Interstate 695 and Maryland Route 570.[1][2] Traversing ten states—Utah, Colorado, Kansas, Missouri, Illinois, Indiana, Ohio, Pennsylvania, West Virginia, and Maryland—I-70 serves as a critical transcontinental corridor facilitating interstate commerce, tourism, and daily travel, largely paralleling the historic U.S. Route 40.[2] The highway's construction, initiated as part of the Dwight D. Eisenhower National System of Interstate and Defense Highways authorized in 1956, presented formidable engineering challenges, particularly in Colorado where it navigates the Rocky Mountains through the Eisenhower–Johnson Memorial Tunnels—the highest vehicular tunnels in the world at over 11,000 feet (3,400 m) elevation—and the serpentine Glenwood Canyon, completed in 1992 using innovative techniques including tunnels, viaducts, and retaining walls to minimize environmental disruption.[3][4][5] These feats underscore I-70's role in advancing national connectivity, enabling efficient transport across diverse terrains from arid deserts to urban centers like Denver, Kansas City, St. Louis, Indianapolis, and Columbus, while supporting economic hubs through dedicated truck facilities in segments from Missouri to Ohio.[6]Overview
Route summary
Interstate 70 (I-70) extends 2,153 miles (3,465 km) eastward from its western terminus at a junction with Interstate 15 near Cove Fort, Utah, to its eastern terminus at an interchange with Interstate 695 and Maryland Route 570 near Baltimore, Maryland.[1] The highway traverses ten states, beginning in the arid terrain of western Utah before ascending the Rocky Mountains in Colorado, crossing the Great Plains through Kansas and Missouri, passing through the Midwest via Illinois, Indiana, and Ohio, navigating the Appalachian region in West Virginia and Pennsylvania, and terminating in the Baltimore metropolitan area.[7] In Utah and Colorado, I-70 follows a challenging alignment through mountainous passes, including the Eisenhower–Edwin C. Johnson Memorial Tunnel at an elevation of 11,158 feet (3,401 m), the highest vehicular tunnel in the Interstate Highway System, and the serpentine Glenwood Canyon section engineered to minimize environmental disruption.[8] East of Denver, the route transitions to flatter farmlands and urban corridors, serving major population centers such as Kansas City, Missouri; St. Louis, Missouri; Indianapolis, Indiana; and Columbus, Ohio, while incorporating viaducts, bridges, and interchanges to accommodate high traffic volumes.[6] The eastern portion crosses the Ohio River multiple times, including via the Fort Henry Bridge in Wheeling, West Virginia, before proceeding through Pennsylvania's rolling hills and concluding in Maryland's coastal plain.[2] Completed in phases from the 1950s through 1992, I-70 ranks as the fifth-longest Interstate Highway, facilitating transcontinental travel and freight movement across diverse geographic and climatic zones.[1]Strategic and economic significance
Interstate 70 functions as a primary east-west transportation corridor across the central United States, spanning over 2,150 miles from Utah to Maryland and enabling efficient movement of goods and people between the Rocky Mountain region, Great Plains, Midwest manufacturing hubs, and eastern ports.[1] It supports substantial freight volumes, with approximately 20,000 trucks traversing segments in Missouri daily and statewide truck freight totaling 31.5 to 46.5 million tons annually, underscoring its role in national supply chains for agriculture, energy resources, and manufactured goods.[9] In rural sections, trucks constitute about 28 percent of traffic, reflecting heavy reliance on the route for bulk commodity transport, while urban areas see 21.5 percent truck usage.[6] Economically, I-70 drives regional prosperity by linking key industries; in Colorado, it provides primary access to a $62.5 billion recreation and tourism sector while enhancing goods shipment efficiency through the Rocky Mountains, where it crosses challenging terrain via engineering feats like the Eisenhower Tunnel.[10][3] Congestion and closures, such as those from accidents, impose significant costs, with 2024 disruptions in Colorado alone exceeding $300 million in lost economic activity due to halted tourism and freight delays.[11] In Missouri, the corridor has acted as an engine for growth, connecting Kansas City and St. Louis and intersecting major north-south routes, with recent $2.8 billion state investments in lane expansions aimed at boosting freight efficiency and accommodating rising volumes.[12][13] Strategically, I-70 forms part of the National System of Interstate and Defense Highways established under the 1956 Federal-Aid Highway Act, which prioritized rapid troop mobilization, evacuation routes, and logistics support in response to Cold War threats and President Eisenhower's World War II experiences with inadequate infrastructure.[14][15] The route's transcontinental alignment facilitates defense-related movements, including access to western military installations via connections like I-15 toward southern California, a region deemed strategically vital during planning.[1] Missouri Department of Transportation assessments highlight I-70's critical defense role, particularly in maintaining resilient supply lines amid disruptions, as evidenced by its use in national emergency responses.[16] As a designated major freight corridor, it mitigates bottlenecks that could impair military logistics, with ongoing upgrades addressing vulnerabilities in high-volume segments.[7]Route description
Utah
Interstate 70 begins at its western terminus, a diamond interchange with Interstate 15 (Veterans Memorial Highway) at milepost 132 near Cove Fort in Millard County, central Utah, marking the end of the overall 2,153-mile route from Baltimore, Maryland.[1] From there, I-70 heads east-northeast across rural terrain, crossing the Pahvant Range and entering Sevier County, where it intersects U.S. Route 89 at exit 17 near Sigurd.[2] The highway then parallels the former alignment of U.S. Route 89 southward through the Sevier Valley, providing access to Richfield—the largest city it serves—at exit 40 via Utah State Route 120 and a business loop.[17] [18] Continuing east from Richfield, I-70 passes Elsinore (exit 37) and reaches Salina at exit 56, where it begins a concurrency with U.S. Route 50, curving southeastward.[17] [18] East of Salina, the route enters a remote 106-mile stretch across the San Rafael Swell, a massive eroded anticline in the Colorado Plateau featuring steep canyons like Little Spotted Wolf Canyon and minimal development, with no exits or services between Salina and Green River (exit 160).[19] [17] This section traverses Fishlake National Forest and exposes layered sedimentary rock formations, emphasizing the highway's role in accessing isolated southeastern Utah.[17] At Green River in Emery County, I-70 meets U.S. Routes 6 and 191 at exits 160–164, including a business loop serving the town, before turning northeast through the Book Cliffs—a series of flat-topped ridges—and paralleling the Green River briefly.[17] [18] The freeway ends after 231 miles (372 km) at the Colorado state line near Thompson Springs in Grand County, continuing seamlessly into Colorado toward Grand Junction.[20] Throughout Utah, I-70 maintains four lanes with occasional passing sections in rural areas, serving primarily as a transcontinental link rather than a local connector due to sparse population density.[17]Colorado
Interstate 70 enters Colorado from Utah at milepost 0 near Fruita in Mesa County, traversing the state for 449.5 miles eastward to the Kansas border near Burlington in Kit Carson County. The route begins on the Western Slope, passing through the Grand Valley and serving Grand Junction, the largest city in the region with over 65,000 residents as of the 2020 census, via exits connecting to local commerce, agriculture, and Colorado National Monument. East of Grand Junction, I-70 follows the Colorado River through De Beque Canyon before entering the 12-mile Glenwood Canyon stretch between Glenwood Springs and Dotsero.[21][22] The Glenwood Canyon section, completed in 1992 after construction began in 1980 at a cost of approximately $490 million, represents a significant engineering achievement, incorporating over 40 bridges and viaducts, five lanes in each direction in places, and four shorter tunnels to preserve the canyon's natural environment while accommodating the highway's alignment along the narrow river corridor. East of Glenwood Springs, I-70 climbs to Vail Pass at an elevation of 10,666 feet (3,252 meters), providing access to ski resorts such as Vail and Beaver Creek via exits and frontage roads. The highway then descends into the Eagle River Valley, passing Silverthorne and Dillon Reservoir, before ascending again to the Eisenhower-Johnson Memorial Tunnels near the Continental Divide.[5][23] The Eisenhower-Johnson Memorial Tunnels, the highest vehicular tunnels in the world at 11,158 feet (3,401 meters) elevation, consist of twin bores totaling about 1.7 miles (2.7 kilometers) in length; the westbound Eisenhower bore opened on March 8, 1973, following construction start on March 15, 1968, while the eastbound Johnson bore opened in 1979 to handle increased traffic and improve safety over Loveland Pass. Eastbound from the tunnels, I-70 descends through the Clear Creek Canyon area, passing Georgetown and Idaho Springs with steep grades and curves managed by runaway truck ramps, before reaching the Front Range foothills near Evergreen and entering the Denver metropolitan area. In Denver, the route interchanges with I-25 and I-270, traversing urban sections with elevated viaducts until exiting the city eastward through Aurora toward the plains.[24][3] Across the eastern plains, I-70 maintains a straight, four-lane alignment past agricultural communities like Strasburg and Limon, serving as a key freight corridor with minimal elevation changes until the Kansas state line at milepost 449.5. The entire Colorado segment, authorized under the Federal-Aid Highway Act of 1956 and built progressively from the 1950s through the 1990s, faced unique challenges in the mountainous 230-mile corridor from Glenwood Springs to Denver due to terrain, weather, and environmental concerns, resulting in delayed completion compared to the flatter eastern portions.[25][26]Kansas
Interstate 70 enters Kansas from Colorado at milepost 0, just west of Kanorado in Sherman County, and extends 423.8 miles eastward to the Missouri state line in Kansas City via the Lewis and Clark Viaduct.[27][28] The route traverses predominantly flat High Plains and prairie terrain, facilitating freight and passenger travel across agricultural regions with minimal elevation changes.[29] Construction of Kansas's segment began in the mid-1950s, with the first completed portion dedicated in November 1956 near Hays, and significant openings including the Junction City to Abilene section on October 9, 1959; most of the highway was open by the mid-1960s.[30][31] In western Kansas, I-70 passes through rural areas with annual average daily traffic (AADT) volumes typically ranging from 5,000 to 10,000 vehicles, serving towns such as Goodland (exit 19, concurrent with U.S. Route 24), Colby (exit 84), and Oakley (exit 159, near Fick Fossil and History Museum).[32] Further east, it reaches Hays (exits 159-164, intersecting U.S. Route 183 and spurring a business loop), Ellis, and Russell, crossing the Smoky Hill River near I-70's central segment where AADT increases to 20,000-30,000 amid growing commercial activity.[28] A key interchange occurs at Salina (exits 252-253), where I-70 meets the northern terminus of I-135, providing access to Wichita southward; here, the highway features six lanes in urban areas and supports higher truck volumes due to regional distribution centers.[27][7] East of Salina, I-70 continues through Abilene (exit 275, historic Eisenhower home nearby), Chapman, and Junction City (exits 295-300, near U.S. Route 77 and Fort Riley military base), with ongoing improvements like the K-18 interchange flyover for better traffic flow.[33] Approaching Topeka, it overlaps briefly with I-470 (a beltway) and the Kansas Turnpike toll road eastbound, intersecting I-335 (a spur to Emporia) and experiencing AADT of around 41,500 through downtown Topeka.[28][34] In Lawrence (exits 360-371), I-70 parallels U.S. Route 40 and meets K-10, with AADT dropping to about 31,900 west of the city before rising again toward the Kansas City metropolitan area.[28] The eastern terminus features complex interchanges including I-435 and I-635, culminating in the viaduct over the Kansas River and rail yards, where AADT exceeds 100,000 vehicles daily, reflecting heavy urban freight and commuter use.[32][27]Missouri
Interstate 70 enters Missouri from Kansas west of Kansas City, marking the start of its approximately 250-mile traversal across the state to the Illinois border east of St. Louis.[35] The highway serves as a primary east-west corridor, paralleling much of historic U.S. Route 40 and facilitating heavy truck traffic between the Kansas City and St. Louis metropolitan areas.[7] In the Kansas City area, I-70 crosses the state line via the Lewis and Clark Viaduct and immediately interchanges with I-670 and I-35, forming a key junction for north-south travel.[35] It proceeds eastward through urban and suburban zones, with major interchanges at I-29 near the Missouri River, I-435 serving the southern suburbs, and I-470 looping to Independence. Beyond the metro, the route passes through Independence and Blue Springs before transitioning to rural terrain near Odessa, where it maintains four lanes with periodic widening projects underway to add capacity.[36] East of Odessa, I-70 continues through farmland and small communities, reaching Columbia approximately 120 miles from the western border, where it intersects U.S. 63 in a complex interchange known for congestion relief efforts.[37] Further east at Kingdom City, it meets U.S. 54, providing access to northern Missouri. The highway then traverses rolling countryside, interchanging with Route 47 near Warrenton and entering the St. Louis exurbs at Wentzville, where I-64 joins as a concurrency eastward.[35] Approaching St. Louis from the west, I-70 crosses the Missouri River via the Blanchette Memorial Bridge near St. Charles and interchanges with I-270 northwest of the city core.[35] It skirts the northern edge of metropolitan St. Louis, passing through Bridgeton and interchanging with I-170, before aligning with I-64 through industrial areas and into downtown St. Louis. The route ends in Missouri at the Stan Musial Veterans Memorial Bridge over the Mississippi River, completed in 2014 to replace the aging Poplar Street Bridge alignment and shorten the path by 1.5 miles.[35] Ongoing Missouri Department of Transportation initiatives aim to expand much of the corridor to three lanes per direction to address growing freight and commuter demands.[38]Illinois
Interstate 70 enters Illinois from Missouri on the Stan Musial Veterans Memorial Bridge, a cable-stayed structure spanning the Mississippi River that opened in 2014 to relieve congestion on older crossings like the Poplar Street Bridge.[39] The highway travels approximately 156 miles (251 km) eastward across southern Illinois, primarily through the Metro-East region and rural farmland, before exiting into Indiana near Marshall.[40] As a key east-west freight corridor, it serves heavy truck traffic connecting St. Louis to Indianapolis and beyond.[41] From the bridge landing near East St. Louis in St. Clair County, I-70 proceeds northeast through industrial and urban areas of the Metro-East, interchanging with I-64 (exit 3) and briefly overlapping it before separating.[41] It continues to I-255 near Collinsville (exit 24), providing access to the southern St. Louis suburbs, then arcs eastward past Troy, where it meets I-55 (exit 30) in a partial cloverleaf interchange.[41] Beyond the Metro-East, the route transitions to flat agricultural terrain, passing through small communities like Highland, Greenville, and Vandalia, with periodic rest areas and service plazas supporting long-haul traffic.[7] Further east, I-70 reaches Effingham in Effingham County, site of a major junction with I-57 (exit 160), which directs north-south traffic toward Chicago and southern Illinois.[41] The interchange, expanded in phases through the 2010s for safety and capacity, handles significant volumes from overlapping freight routes.[42] From Effingham, the highway continues northeast through Teutopolis and Greenup, remaining a four-lane divided freeway with minimal urban development until the Indiana state line at milepost 160, where it enters Vigo County.[41] Throughout its Illinois span, I-70 overlays much of historic U.S. Route 40, facilitating commerce in corn and soybean regions while avoiding major terrain obstacles.[41]Indiana
Interstate 70 enters Indiana from Illinois in Vigo County, approximately 5 miles west of Terre Haute, crossing the Wabash River near the state line. The highway spans 157 miles eastward through central Indiana, primarily paralleling U.S. Route 40 across Vigo, Clay, Putnam, Hendricks, Marion, Hancock, Henry, and Wayne counties before exiting into Ohio east of Richmond. It functions as a key freight and commuter corridor, linking western Indiana's manufacturing hubs to the Indianapolis metropolitan area and eastern rural communities.[40][43] West of Indianapolis, I-70 passes south of Terre Haute with a major interchange at U.S. 41/U.S. 150 (exit 7), providing access to the city's downtown and Indiana State University. Further east, it intersects State Road 59 near Brazil and U.S. 40 directly before reaching the Indianapolis suburbs in Hendricks County. In the capital region, I-70 joins I-465 at the southwest interchange (exit 68), forming the outer beltway's west leg, then reenters the urban core via the South Split with I-65, crossing the White River, and reconvening at the North Split before exiting Marion County. Eastbound, it serves Greenfield via State Road 9 and Centerville before terminating at the Ohio line near Richmond, with interchanges including U.S. 35 and State Road 1.[44][45] The route features relatively flat terrain with minimal elevation changes, lacking tunnels but including bridges over the Wabash, White, and Big Blue rivers. In Indianapolis, the downtown segment underwent the Super 70 reconstruction from 2002 to 2007, widening lanes to eight, adding 14-foot shoulders, and raising clearances to accommodate larger vehicles, addressing chronic congestion from over 100,000 daily vehicles. Ongoing efforts include the I-65/I-70 North Split interchange rebuild, started in 2021 with a $645 million budget, replacing 13 bridges and improving ramps for better traffic flow expected by late 2024. Eastern improvements under the Revive I-70 project, initiated in 2024, focus on pavement rehabilitation and bridge preservation from Cambridge City to the state line.[46][47][48] Construction of I-70 in Indiana began in the late 1950s following federal Interstate Highway System approval in 1956, with Governor Harold Handley committing to the state's 932-mile network costing $1 billion. Early segments near Richmond opened by 1960, while Terre Haute-area portions followed in the early 1960s; the full route was completed by 1976. Right-of-way acquisition and bidding for eastern sections occurred as early as March 1959, reflecting rapid postwar infrastructure push amid growing auto traffic paralleling the National Road (U.S. 40).[49][50]Ohio
Interstate 70 spans 225 miles (363 km) across Ohio, entering from Indiana east of Richmond and exiting to West Virginia near Bridgeport by crossing the Ohio River into Wheeling.[51][2] The route serves as a vital east-west artery, facilitating freight and commuter traffic through urban centers Dayton and Columbus while traversing rural Appalachian terrain in the east.[7] In western Ohio, I-70 proceeds eastward from the Indiana state line through Preble County, bypassing Eaton to the north before entering Montgomery County and the Dayton metropolitan area. There, it interchanges with Interstate 75 in Huber Heights, providing connectivity to southern Michigan and Cincinnati via I-75. Continuing east-southeast through Clark County, the highway avoids Springfield to the south, transitioning into Madison and Franklin Counties toward Columbus.[2][51] Approaching Columbus, I-70 intersects the southern terminus of Interstate 270, the metropolitan outerbelt, west of the city, then passes north of downtown where it meets Interstate 71 in a complex braided interchange near the Scioto River. Interstate 670 spurs northeast from I-70 west of downtown, offering access to Port Columbus International Airport and linking to I-270 east. East of Columbus in Licking County, the route parallels U.S. Route 40 through Reynoldsburg before veering northeast into rural areas.[52][51] In eastern Ohio, I-70 enters Muskingum County and curves through Zanesville, where it follows a tight alignment along the Muskingum River before expanding into four lanes eastward. The highway then proceeds through Guernsey County to Cambridge, site of the expansive stack interchange with Interstate 77, covering over 300 acres and once promoted as the world's largest by land area. In Belmont County, I-70 serves St. Clairsville and the Ohio Valley Mall before reaching Bridgeport, terminating at the West Virginia state line via a bridge over the Ohio River's west branch to Wheeling Island.[53][51][2]West Virginia
Interstate 70 enters West Virginia from Ohio at milepost 0 by crossing the Ohio River via the Fort Henry Bridge, a four-lane tied-arch structure completed in 1955 that spans 2,270 feet and carries concurrent routes I-70, U.S. Route 40, and U.S. Route 250.[54][55] The bridge connects Bridgeport, Ohio, directly to Wheeling in Ohio County, handling over 60,000 vehicles daily as the initial segment of I-70 in the state.[54] Immediately after the bridge, I-70 reaches its first interchange at Wheeling Island (exit 0, westbound only), providing access to Zane Street and the Wheeling Island Racetrack and Gaming Resort.[56] The highway then proceeds eastward through urban Wheeling, intersecting U.S. Route 40 and West Virginia Route 2 at exit 2, a partial cloverleaf interchange serving downtown Wheeling and local traffic.[57] Further east at exit 5, I-70 meets West Virginia Route 2 again, offering connections to Wellsburg and industrial areas along the Ohio River.[57] Beyond Wheeling, the route transitions to more suburban and rural terrain in the Northern Panhandle, passing south of Elm Grove (via West Virginia Route 88 access) and interchanging with West Virginia Route 27 at exit 10 near Triadelphia and Valley Grove for regional access.[57] The entire 14.45-mile segment in West Virginia, the shortest for I-70 in any state, concludes at milepost 14.45 where it crosses into Pennsylvania without additional interchanges, featuring a brief single-lane tunnel east of Wheeling that limits capacity to one through lane per direction.[57][2]Pennsylvania
Interstate 70 enters Pennsylvania from West Virginia in Donegal Township, Washington County, as a four-lane divided freeway traversing rural terrain in the southwestern part of the state. The route heads northeast, interchanging with Pennsylvania Route 231 near the state line and Pennsylvania Route 617 before reaching a cloverleaf junction with Interstate 79 at mile marker 11 south of Washington, facilitating connections to Pittsburgh northward. In Washington, I-70 meets Pennsylvania Route 18 via a diamond interchange and continues east through industrial suburbs, crossing the Monongahela River and providing access via Pennsylvania Route 88 in North Charleroi Township, Pennsylvania Route 906 in Fallowfield Township, and Pennsylvania Route 51 in Rostraver Township, Westmoreland County.[58][59] Eastbound, I-70 briefly enters Fayette County, interchanging with U.S. Route 40 Business and Pennsylvania Route 43 near Uniontown before returning to Westmoreland County and terminating its independent alignment at New Stanton. There, at mile marker 57, it merges into the westbound lanes of the Pennsylvania Turnpike (Interstate 76), initiating a 103-mile concurrency eastward through the Allegheny Mountains across Fayette, Somerset, and Bedford counties. This tolled section, maintained by the Pennsylvania Turnpike Commission, features limited-access interchanges including U.S. Route 119 in Dunbar Township, Pennsylvania Route 281 in Somerset, Interstate 99 and U.S. Route 220 near Bedford, and U.S. Route 30 at the Breezewood interchange (Turnpike exit 161). The pre-freeway alignment west of the turnpike, spanning 38 miles from Washington to New Stanton, retains substandard geometric features from its origins as Pennsylvania Route 71.[60][59][2] At Breezewood in East Providence Township, Bedford County, I-70 diverges southeast from the turnpike via dedicated ramps, bypassing the local commercial district on a short, non-tolled freeway segment that parallels U.S. Route 30. The route crosses the Maryland state line near the Potomac River after roughly 6 miles, entering Allegany County, Maryland, en route to Hancock. PennDOT District 12 oversees maintenance from the West Virginia border to New Stanton, while the turnpike concurrency falls under the Pennsylvania Turnpike Commission. The entirety of I-70 in Pennsylvania measures 167.92 miles (270.24 km).[61][62][63]Maryland
Interstate 70 enters Maryland from Pennsylvania in Washington County near Hancock. Shortly after the state line, it meets the eastern terminus of Interstate 68 at a trumpet interchange.[64][64] The route continues east through Washington County, providing access to Hagerstown via interchanges with Maryland Route 65 and U.S. Route 40 Alternate.[65][66] It then curves southeast into Frederick County, bypassing South Mountain and entering the city of Frederick, where key interchanges include those with U.S. Route 40, U.S. Route 15, Maryland Route 85, and Interstate 270 (a spur of the Capital Beltway).[67][65] Recent improvements in the Frederick area include the reconstruction of the interchange with Maryland Route 85 and Maryland Route 355, completed to enhance traffic flow and safety.[68] East of Frederick, I-70 proceeds through rural areas of Carroll and Howard counties, passing near Mount Airy and Ellicott City with connections to U.S. Route 29 (Columbia Pike) and U.S. Route 40.[69] The highway enters Baltimore County and terminates at a partial cloverleaf interchange with Interstate 695 (Baltimore Beltway) and Maryland Route 570 in Woodlawn, just west of Baltimore, at Security Boulevard (Maryland Route 122).[64][70] The entire Maryland portion measures 94.38 miles, traversing Washington, Frederick, Carroll, Howard, and Baltimore counties.[64]Engineering and design features
Major tunnels and bridges
The Eisenhower–Johnson Memorial Tunnels, located west of Denver in Colorado, represent the highest vehicular tunnels in the world at an elevation of 11,158 feet (3,401 m), carrying I-70 under the Continental Divide.[3] The westbound Eisenhower bore, 1.7 miles (2.7 km) long, opened to traffic on March 26, 1973, after construction began on March 15, 1968.[24] The eastbound Johnson bore opened on December 21, 1979, providing dual bores for safer bidirectional travel.[71] These tunnels eliminated the need for hazardous winter travel over Loveland Pass and handle over 30,000 vehicles daily, with metering systems to manage peak traffic.[24] In Glenwood Canyon, Colorado, I-70 incorporates three tunnels—No. 1, No. 2, and No. 3—along with over 40 bridges and viaducts to navigate the narrow, steep terrain while minimizing environmental impact.[5] Completed in 1993, this 12-mile (19 km) section features innovative engineering, including 15 miles of retaining walls and structures like the Hanging Lake Viaduct, which spans a sensitive area along the Colorado River.[72] These elements allow the highway to follow the river's contours, reducing excavation and preserving the canyon's ecology.[5] The Fort Henry Bridge, a tied-arch structure in Wheeling, West Virginia, crosses the Ohio River, carrying I-70, U.S. Route 40, and U.S. Route 250.[73] Opened in 1955 after four years of construction, the 2,270-foot (692 m) bridge utilized 6,700 tons of steel and accommodates over 60,000 vehicles daily as the first segment of I-70 in the state.[55] [54] Its design includes four lanes and riveted construction, supporting interstate connectivity across the river valley.[74] Other notable bridges include various viaducts in Colorado's mountainous sections, but the Eisenhower–Johnson Tunnels and Fort Henry Bridge stand out for their scale and strategic importance in overcoming topographic barriers.[3]Terrain challenges and innovations
Interstate 70 encounters significant terrain obstacles in its western segments, particularly through the rugged landscapes of Utah and Colorado, where it ascends the Rocky Mountains and navigates narrow canyons and high plateaus. In Utah, the route crosses the San Rafael Swell, a large anticlinal uplift featuring steep cliffs and layered rock formations of Jurassic age, necessitating deep road cuts to penetrate the San Rafael Reef on the eastern flank.[75] These cuts exposed Morrison Formation strata but required careful blasting and stabilization to handle the fractured geology and erosion risks inherent to the desert terrain. The most formidable challenges arise in Colorado, where I-70 climbs over 6,000 feet in elevation from the eastern plains to the Continental Divide, confronting steep grades, avalanche-prone slopes, and unstable rock faces prone to falls. Pre-interstate routes like U.S. Route 40 over Loveland Pass featured grades exceeding 7% and frequent closures due to snow and ice, prompting the need for innovative solutions to maintain year-round access.[3] The Eisenhower-Johnson Memorial Tunnels, completed with the west bore opening on March 26, 1973, and the east bore on December 21, 1979, addressed this by boring twin tunnels 1.7 miles long each through the Continental Divide at an elevation of 11,158 feet, the highest point on the Interstate Highway System and the world's highest vehicular tunnels.[76] This engineering feat involved overcoming water inflows exceeding 1,000 gallons per minute during excavation, seismic risks, and ventilation demands for high-altitude traffic, using advanced drilling and lining techniques with reinforced concrete.[3] Further west in Glenwood Canyon, I-70 threads a 12-mile stretch along the Colorado River amid sheer granite walls rising over 1,000 feet, where space constraints and environmental protections limited widening options. Construction from 1980 to 1992 employed context-sensitive design principles, including 40 bridges—some double-decked to stack roadways—and extensive retaining walls covering 18 miles to support cuts into the canyon walls, minimizing riparian disruption.[4] Innovations such as automated rock bolting, shotcrete stabilization, and revegetation with native species preserved the area's ecology while achieving a maximum grade of 3.4%, earning the project multiple awards for blending infrastructure with natural contours.[77] In the Appalachians of West Virginia and Pennsylvania, terrain shifts to rolling hills and river valleys, presenting challenges like frequent flooding and soft soils, addressed through elevated alignments and drainage innovations, though less extreme than western segments. Overall, these adaptations—tunnels, viaducts, and geotechnical stabilizations—enabled I-70 to span diverse physiographic provinces with grades rarely exceeding Interstate standards of 3-4% in mountains, facilitating reliable transcontinental travel.[78]History
Planning and federal designation
The planning of Interstate 70 formed part of the national effort to develop a unified highway system, with preliminary route designations emerging from the Federal-Aid Highway Act of 1944, which authorized a 40,000-mile "National System of Interstate Highways" prioritized for defense and commerce.[1] The Bureau of Public Roads, tasked with mapping the network, aligned much of the proposed I-70 corridor with the established path of U.S. Route 40 to leverage existing roadways while addressing transcontinental needs from the Midwest to the Atlantic seaboard, incorporating military input for strategic connectivity.[1] Federal funding and formal authorization arrived with the Federal-Aid Highway Act of 1956, enacted on June 29, 1956, which committed $25 billion over 13 years for 41,000 miles of limited-access highways under the National System of Interstate and Defense Highways, emphasizing rapid construction and 90% federal cost coverage.[79] This legislation enabled detailed route approvals, with the American Association of State Highway Officials (AASHO) finalizing Interstate numbering and designations in September 1957, adapting principles from the U.S. Highway system where even numbers denoted east-west routes.[80] I-70 was officially designated as an original Interstate on August 14, 1957, spanning approximately 2,153 miles from its western terminus near Cove Fort, Utah (at Interstate 15), eastward through Colorado, Kansas, Missouri, Illinois, Indiana, Ohio, West Virginia, Pennsylvania, and Maryland to Baltimore.[2] The western extension to Utah, influenced by military planners seeking improved access without routing through Salt Lake City, was enabled by 1957 congressional additions of 1,000 miles to the system.[1] State agencies then refined local alignments in coordination with the Bureau of Public Roads, balancing terrain challenges like the Rocky Mountains with economic and traffic projections.[19]Construction phases and timelines
The construction of Interstate 70 was authorized under the Federal-Aid Highway Act of 1956, which established the Interstate Highway System. Initial contracts were awarded in Missouri on August 2, 1956, marking the first interstate projects nationwide, with paving beginning in Kansas on September 26, 1956.[81][80] The first completed segment opened in Indiana on November 14, 1956, spanning a short portion and designated as the inaugural section of the national system.[2] Construction progressed variably by state, with flatter midwestern terrains allowing faster completion in the late 1950s and 1960s. In Missouri, early work focused on upgrading U.S. Route 40 alignments in St. Charles County. Kansas completed initial segments in the early 1960s, with the final 19-mile portion between Goodland and the Colorado border opening on June 17, 1970.[82][30] Illinois' brief 2-mile segment through the St. Louis metropolitan area was integrated concurrently with Missouri's efforts. Indiana advanced multiple sections around Indianapolis during this period, though some urban realignments extended into the 1990s. Ohio's portions, including approaches to Columbus, were largely finished by the mid-1960s. Eastern segments faced fewer topographic hurdles but urban complexities. West Virginia opened initial portions in 1963, achieving full completion by 1971.[83] In Pennsylvania, key links such as the connection to the Pennsylvania Turnpike were constructed between 1966 and 1968. Maryland's segment to Baltimore integrated with local routes in the early 1960s.[59] Western phases encountered severe terrain challenges, extending timelines significantly. In Colorado, construction spanned from 1961 to 1977 for most of the 449-mile route, with detailed segmental openings: the I-25 junction viaduct in Denver completed September 12, 1964; eastern plains sections like Byers to Bennett in 1964 and Limon bypasses in 1975; mountain passes including the Eisenhower Tunnel approaches by 1972.[84] Utah's 114-mile spur from Cove Fort eastward was built gradually, reaching completion in 1990 due to remote desert conditions and funding constraints.[1] The final major undeveloped section, Glenwood Canyon in Colorado, opened October 14, 1992, incorporating extensive environmental mitigations and engineering innovations.[22]Key engineering milestones
The Fort Henry Bridge, a tied-arch structure spanning the Ohio River in Wheeling, West Virginia, opened to traffic on October 1, 1955, marking one of the earliest completed segments of what would become Interstate 70.[55] This 2,270-foot-long bridge, constructed with 6,700 tons of steel and 21,300 cubic yards of concrete at a cost exceeding $6 million, facilitated the initial four-lane connection for U.S. Routes 40 and 250, later integrated into I-70.[55] Its design as only the second tied-arch bridge over the Ohio River represented an advancement in cantilever construction techniques for river crossings in the Interstate era.[85] Construction of the Eisenhower-Johnson Memorial Tunnels began on March 15, 1968, addressing the challenge of traversing the Continental Divide at Loveland Pass in Colorado's Rocky Mountains.[76] The westbound Eisenhower Tunnel bore, completed in 1973 after five years of excavation through unstable granite and schist, opened as the highest vehicular tunnel in the world at 11,158 feet elevation.[24] The eastbound Edwin C. Johnson bore followed, with construction starting in 1975 and completion in 1979, providing twin bores to handle bidirectional traffic and improve safety over the previous winding mountain route.[76] These tunnels, totaling 1.7 miles, employed innovative ventilation, drainage, and rock stabilization methods to mitigate geological risks, enabling year-round access along I-70.[3] The 12-mile Glenwood Canyon segment in Colorado, finalized on October 14, 1992, exemplified advanced environmental engineering amid rugged terrain.[4] Completed after 12 years and $490 million in costs, the project incorporated curved alignments, 40 bridges and viaducts, extensive retaining walls, and terraced roadways to minimize disruption to the canyon's ecosystem and scenic Colorado River corridor.[86] Innovations included elevated westbound lanes on cantilevered structures, state-of-the-art rock excavation, and revegetation techniques, balancing Interstate standards with federal environmental mandates under the National Environmental Policy Act.[87] This final link in Colorado's I-70 mountain corridor resolved long-standing topographic barriers through consensus-driven design processes involving multiple stakeholders.[4]Auxiliary and related routes
Spur, loop, and business routes
Interstate 70 is served by multiple business loops and spurs that provide access to bypassed urban and commercial districts, primarily in the western United States. These routes typically follow pre-freeway alignments of U.S. Route 40 or 6, maintaining local traffic while directing through-traffic to the mainline. Auxiliary spurs and loops, designated as three-digit Interstate routes, are limited, with I-470 in Kansas functioning as a partial loop around Topeka, connecting I-70/I-35 to provide southern bypass capacity.[88] In Utah, three business routes exist: a 3-mile loop through Richfield via State Route 120 between exits 37 and 40; a 1.8-mile spur in Salina from exit 54, cosigned with U.S. Routes 50 and 89; and a loop through Green River along SR-19 between exits 158 and 162, serving as the primary local route.[89] Colorado hosts the most extensive network, including signed business loops in Grand Junction (13.3 miles along U.S. 6/50 from exits 26 to 37, with ongoing reconstruction for pavement and drainage as of August 2024), Idaho Springs (2.7 miles from exits 239 to 241), the Golden-Denver area (27.5 miles cosigned with U.S. 40/287), Limon (4.3 miles from exits 359 to 361), and Burlington (2 miles cosigned with U.S. 385 from exits 437 to 438). Several short unsigned spurs exist, such as in Silt (0.2 miles) and Eagle (0.3 miles), designated internally by the Colorado Department of Transportation for local connections.[90][89] Kansas has no active signed business routes for I-70, though former loops existed in cities like Colby (11.3 miles, decommissioned) and Hays; proposals for new ones have been rejected to prioritize mainline capacity.[89] In Missouri, business loops include one in Boonville (exits 101 to 106, cosigned with U.S. 40/MO 5), Columbia (2.8 miles from exits 125 to 128, cosigned with U.S. 63, with bridge replacements over it completed in recent design-build projects), and St. Charles (exits 228 to 229, cosigned with MO 94).[91][89] Further east, business routes are scarce; Ohio once had a 15.4-mile loop in Springfield, but it has been decommissioned. No such routes exist in Illinois, Indiana, West Virginia, Pennsylvania, or Maryland, where I-70 alignments generally traverse urban areas directly or via overlaps rather than dedicated business paths.[89]| State | Type | Location | Length (miles) | Key Features |
|---|---|---|---|---|
| Utah | Business Loop | Richfield | 3 | SR-120, exits 37-40 |
| Utah | Business Spur | Salina | 1.8 | Cosigned US 50/89, exit 54 |
| Utah | Business Loop | Green River | ~4 | SR-19, exits 158-162 |
| Colorado | Business Loop | Grand Junction | 13.3 | US 6/50, exits 26-37; under reconstruction[90] |
| Missouri | Business Loop | Columbia | 2.8 | US 63, exits 125-128; bridges replaced[91] |