The first completed section (i.e. open to traffic) was I-70 in Kansas. From the Federal Highway Administration's website: "On Nov. 14, 1956, Gov. Fred Hall participated in a ribbon-cutting to open the newly paved road, and a sign was posted, identifying this section of I-70 as the "first project in the United States completed under the provisions of the new Federal-Aid Highway Act of 1956."
Interstate 70, Interstate 76, Interstate 25, US Highway 50, US Highway 24, US Highway 85, US Highway 87, US Highway 287, US Highway 40, Colorado Route 9... those are some of your major thoroughfares.
The US Interstate Highway that runs through Helena, Montana is Interstate 15.
The US Interstate highway which connects Kalamazoo, MI to Stevensville, MI is Interstate 94.
As of 2012, the US interstate highway system includes almost 50,000 miles.
Dwight Eisenhower was President of the US when the Interstate highway system was formed.
Longest interstate highway is I-90.
US Interstate 30 is the highway that connects Texarkana, Arkansas to Arkedelphia, Arkansas.
US Interstate highway 135 connects Salina Kansas to Newton Kansas.
Interstate 70 is the US highway that connects Brewster, KS to Salina, KS.
interstate 80.
The best way to travel from Nashville Tennessee to Knoxville Tennessee is by Interstate 40.
US Interstate highway 20 connects Atlanta to Birmingham Alabama.