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National Highway System (NHS) Maps - v12
The National Highway System (NHS) was established on November 28, 1995, through the National Highway System Designation Act of 1995; the system was expanded when the Transportation Equity Act for the 21st Century was adopted on June 9, 1998. Various criteria have been used in the selection process in order to meet the following objective:
"Provide an interconnected system of principal arterial routes which will serve major population centers, international border crossings, ports, airports, public transportation facilities, and other intermodal transportation facilities and other major travel destinations; meet national defense requirements; and serve interstate and interregional travel."
-- from the Intermodal Surface Transportation Efficiency Act of 1991 (ISTEA), Section 1006
Federal guidelines for the selection process include a functional classification requirement. With few exceptions, the NHS has been selected from among all the routes classified as principal arterial. Existing and future Interstate Highways (freeways) -- a type of principal arterial -- are automatically included within the NHS. In those few cases where an NHS route is something other than a freeway, or another kind of principal arterial, it has been selected based on its connection to a military facility or to a major intermodal terminal (intermodal terminal types are airport, Amtrak, rail/truck, bus, and ferry).
Mileage Information: For the entire country, the National Highway System includes 158,674 miles of Interstate and other routes. Michigan's NHS has 4,720 total miles -- this breaks down into 1,241 miles of Interstate; 3,207 miles of other state-owned routes; and 305 miles of streets and roads under either city or county jurisdiction.
For NFC related information,