List of Interstate Highways
There are 70 primary Interstate Highways in the Interstate Highway System, a network of controlled-access freeways in the United States. They are assigned one- or two-digit route numbers, whereas their associated "auxiliary" Interstate Highways receive three-digit route numbers. Typically, odd-numbered Interstates run south-north, with lower numbers in the west and higher numbers in the east; even-numbered Interstates run west-east, with lower numbers in the south and higher numbers in the north. Highways whose route numbers are divisible by "5" usually represent major coast-to-coast or border-to-border routes (ex. I-10 travels from Santa Monica, California, to Jacksonville, Florida, traveling from the Pacific to Atlantic oceans). Additionally, auxiliary highways have their numbering system where a different number prefixes the number of its parent highway.
List of future Interstate Highways
The FAST Act added the US 70 corridor between Garner and Morehead City, North Carolina, to the Interstate system by defining it as, first, High Priority Corridor #82, and subsequently designating it as a future Interstate. The Regional Transportation Alliance expected this corridor to be called Interstate 46 or another suitable designation. At a meeting in La Grange, North Carolina, on March 17, 2016, the Super 70 Corridor Commission recommended that the designation of Interstate 50 be sought for the US 70 Interstate corridor. The rationale for the I-50 numerical selection was cited as a number not in conflict with either an existing Interstate designation or currently applied to a U.S. Highway within North Carolina. This recommendation was forwarded to NCDOT for submission to AASHTO.