Interstate 70 was one of the first Interstate Highways to be built on many different levels, according to the Federal Highway Administration article “Three States Claim First Interstate Highway” by Richard F. Weingroff that appeared in Public Roads. Three sections of Interstate 70 in Pennsylvania, Missouri and Kansas could each claim to be the “first” section of Interstate Highway to be built.
A sign in St. Charles County reminds motorists of Missouri’s claim of the “First Interstate Highway” with this sign posted on westbound Interstate 70 northwest of St. Louis. Photo by Joe Balsarotti (10/17/05).
The Pennsylvania Turnpike today incorporates portions of both I-70 and Interstate 76. The section between Irwin (Exit 67, near the U.S. 30 southeast of Pittsburgh) and Carlisle (Exit 226, near the junction with Interstate 81) opened to traffic on October 1, 1940. Although the Turnpike did not have I-70 shields on it when it opened, this portion of I-70/76 could be considered the first Interstate highway. However, this toll facility was not built with Interstate Highway Funds. The Interstate designation was added to the Turnpike well after the roadway opened.
The other two instances of “first Interstate highway” claims are directly related to the freeways built with Interstate Highway Funds. Within Missouri, the section of I-70 (Mark Twain Expressway) in St. Charles County was the first Interstate Highway project to be awarded and to start construction (contract awarded on August 2, 1956, and construction began on August 13, 1956). Within Kansas, a two lane section of I-70 (U.S. 40) several miles west of Topeka also could claim “first Interstate highway” because it was the first segment to be completed with federal Interstate Highway funds, even though construction had begun prior to that point. This section of Interstate 70 opened on November 14, 1956. Signs along the route at the time stated that this section of I-70 was the “first project in the United States completed under the provisions of the new Federal-Aid Highway Act of 1956.”
This view of Interstate 70 looks east through the San Rafael Swell toward Green River in central Utah from Ghost Rock Summit. The freeway occupies a narrow footprint as it ascends toward the top of the swell. Photo by Jeff Royston, 09/16/06.
Interstate 70 begins in sparsely populated central Utah from an exchange with I-15 near Cove Fort. I-70 follows former Utah State Route 4 between Interstate 15 and U.S. 89, then parallels old U.S. 89 from Sevier north to Salina via Richfield through the Sevier Valley. Originally, Interstate 70 was programmed to begin in Denver; however, a later addition, made public on October 18, 1957, extended the route west to Cove Fort to allow for greater access to Southern California.10 Some would have preferred that Interstate 70 turn northwest at Green River toward Spanish Fork, thus offering a freeway route to Salt Lake City; however, the federal plan preferred sending the route southwest to provide access to Southern California via I-15.
Interstate 70 leaves U.S. 89 at Salina, Utah and converges with U.S. 50. I-70/U.S. 50 cross 110 miles of sparsely populated land between Salina and Green River. U.S. 50 was rerouted onto Interstate 70 in 1976 from its former alignment it previously shared with U.S. 6 between Delta and Green River. East from Salina, the freeway ascends to Salina Canyon Summit/Emigrant Pass (elevation 7,923 feet) in Fishlake National Forest, then crosses the Wasatch Plateau. Beyond the exchange with SR 10, Interstate 70 enters the San Rafael Swell. I-70 through this scenic area was mostly built as a two lane freeway, and was the last section of nationally expanded to four lanes. Through the swell, freeway construction required removal of 3.5 million yards of excavation at Spotted Wolf Canyon and the construction of two steel arch bridges over deep Eagle Canyon (near Milepost 120) in 1965 (eastbound) and 1990 (westbound; constructed by OlsenBeal).11
The 70 mile long section of I-70 with two lanes opened to traffic on November 5, 1970, and it is still the longest section of Interstate Highway to open at one time.10 Four lane expansion was completed in stages, with the route completely up to Interstate standards following the opening of the second Eagle Canyon bridge on September 28, 1990. The freeway runs through such unpopulated territory that Interstate 70 still has no motorist services between Salina and Green River for 110 miles. I-70 was not preceded by any kind of two lane highway due to the rugged nature of the scenic San Rafael Swell in Emery County — neither U.S. 50 nor SR 4 were routed on the location of today’s freeway alignment.10 This segment cost $183.5 million to complete.
Interstate 70 proceeds east over the Green River and passes by the southern end of the Book Cliffs through the Grand Valley before entering Colorado. U.S. 6 combines with I-70/U.S. 6 east from the city of Green River into the Centennial State.