Interstate 70

Interstate 70 is a major east–west Interstate Highway in the United States that runs from Interstate 15 near Cove Fort, Utah, to a park and ride lot near Baltimore, Maryland. It is the fourth-longest Interstate Highway in the nation, traversing ten states and serving as a critical transportation artery through the Great Plains, Appalachian Mountains, and Midwestern United States. The highway connects major cities including Denver, Kansas City, St. Louis, Indianapolis, Columbus, and Pittsburgh, facilitating national commerce and travel.

Route description

From its western terminus at Interstate 15 in the arid Sevier Valley of Utah, the route ascends into the Colorado Plateau before crossing the formidable Rocky Mountains in Colorado, passing through the Eisenhower–Johnson Memorial Tunnel under the Continental Divide. It descends onto the High Plains near Denver and continues east across the vast Great Plains of Kansas, where it is noted for a 424-mile segment with no federally-mandated interchanges. Entering the Midwestern United States, it serves the metropolitan areas of Kansas City and St. Louis before crossing the Mississippi River into Illinois. The highway cuts across the agricultural Corn Belt of Indiana and Ohio, skirts the northern suburbs of Columbus, and then challenges the rugged terrain of the Appalachian Mountains in West Virginia and Pennsylvania, including a steep descent at Fulton County. It finally terminates at a park and ride facility near Baltimore, just short of Interstate 695 (the Baltimore Beltway).

History

The highway's genesis lies in the Federal-Aid Highway Act of 1956, championed by President Dwight D. Eisenhower, who was inspired by the German autobahn system observed after World War II. Construction began shortly after the act's passage, with the first section opening in Kansas in 1956. The most formidable engineering challenges were encountered in Colorado, where the construction of the Eisenhower–Johnson Memorial Tunnel (completed in 1979) and the ascent through Glenwood Canyon (finished in 1992) required decades of work and became some of the most expensive Interstate Highway projects per mile. In the east, routing through the mountains of Pennsylvania and West Virginia involved extensive cut and fill and bridge construction, with the final segment opening in 1985 near Wheeling. The route's numbering follows the AASHTO scheme for major east-west routes, with its path largely supplanting older U.S. Route 40 and paralleling the historic National Road.

Major intersections

From west to east, key junctions include its western terminus at Interstate 15 in Utah and a pivotal interchange with Interstate 25 in Denver, Colorado. In Kansas, it intersects Interstate 135 at Salina and Interstate 435 around Kansas City. Critical junctions in Missouri include interchanges with Interstate 29 and Interstate 35 in Kansas City, and Interstate 44 and Interstate 55 in St. Louis. After crossing the Mississippi River, it meets Interstate 55 again and Interstate 57 in Illinois. In Indiana, it converges with Interstate 65 in Indianapolis and Interstate 69 near Fishers. Ohio intersections include Interstate 75 in Dayton and Interstate 71 in Columbus. In West Virginia, it briefly merges with Interstate 79 near Washington, Pennsylvania, before intersecting Interstate 76 (the Pennsylvania Turnpike) near New Stanton. Its easternmost major interchange is with Interstate 695 near Baltimore, Maryland.

Auxiliary routes

Several three-digit auxiliary Interstate Highways branch from the mainline to serve metropolitan areas. These include Interstate 270 and Interstate 470 in the Denver area, and Interstate 670 serving downtown Kansas City. In Missouri, Interstate 170 provides a link in St. Louis County, while Interstate 270 forms a beltway around St. Louis. Interstate 465 encircles Indianapolis, and Interstate 270 forms the outer belt around Columbus. In Pennsylvania, Interstate 376 provides a key link to Pittsburgh, and Interstate 476 (the Northeast Extension) intersects near Allentown. Maryland's primary auxiliary is Interstate 270, a vital commuter route toward Washington, D.C..

Category:Interstate Highways Category:Transportation in the United States