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.
Interstate 49
Although not part of the original 1957 interstate highway plan, residents of Missouri, Arkansas and Louisiana began campaigning for the highway in 1965 via the "US 71 - I-29 Association." The campaign called for Interstate 29 to be extended south from Kansas City to New Orleans following much of the route along US 71. The plan called for creating a limited access expressway from New Orleans to the Canadian border and on to Winnipeg (via Manitoba Highway 75). The highway is not named Interstate 29 because of interstate naming rules. The rules state that north-south roads are odd numbered and the highways are named in increasing order from west to east. Since there are an Interstate 35 and an Interstate 45 to the west and an Interstate 55 to the east Interstate 49 was chosen for the name.