• Groundbreaking ceremony for the first official stretch of Interstate Highway on 31 August 1956, outside of Topeka, Kansas. This “first” is disputed by other municipalities.

  • Officials in Laclede County, Missouri also lay claim to the first federally funded strip of interstate road.

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National Highway System

Road building, supervised by the Army Corps of Engineers and many private contractors, was done in multiple locations at once, and the main routes, known unofficially as superhighways, were linked as they were finished. Superhighways are the flagship roads of the IDHS, where autos travel long distances between entry and exit. These limited access roads (few ramps exist outside of urban areas) are free of traffic signals, intersections and sharp curves to allow high speeds. Large medians, shoulders and other safety features help protect vehicles if they suddenly leave the pavement, and all crossings are grade-separated; that is, they pass either above or below the roadway, never across. Consider Interstate 10 in the Southern U.S., I-90 in the North (the longest route in the system at 3101 miles) and 95, running North-South between New England and Florida.