What is List of Interstate Highways?
[[Image:Map of current Interstates.svg|450px|thumb|right|Interstate Highways in the 48 states that border each other. Purple routes are currently built and open freeways, blue are currently open spur routes, and green is proposed routes, future roads, or those being built.]] [[File:I-blank.svg|150px|thumb|right|The sign used to mark an interstate.]] '''Primary Interstate Highways''' are the major [[Interstate Highway|interstate highway]]s of the [[United States]] and have a one or two-digit route number. ''Even'' (0, 2, 4, 6, or 8) route numbers are given to east/west routes, with the smaller numbered routes in the south ([[Interstate 10|I-10]]) and bigger numbered routes in the north ([[Interstate 90|I-90]]). Similarly, ''odd'' (1, 3, 5, 7, or 9) route numbers are given to north/south routes, with the smaller numbered routes in the west ([[Interstate 5|I-5]]) and the bigger numbered routes in the east ([[Interstate 95|I-95]]). Routes that end in a 0 or a 5 are major routes in the system. These Interstates generally go from coast to coast or from the bottom to the top of the U.S. For example, Interstate 5 goes from the Mexican Border at [[San Diego, California]] to the Canadian Border at [[Blaine, Washington]]. Likewise, Interstate 10, the southernmost cross-country Interstate Highway, goes from [[Santa Monica, California]] on the west coast to [[Jacksonville, Florida]] on the east coast. The longest Interstate Highway in the United States is Interstate 90. There are five sets of numbers that are used more than once throughout the system; the highways whose numbers are used more than once are separated by big distances to avoid confusion. Below, these are made separate from each other by West and East. [[Three-digit Interstate]]s are spur or loop Interstates that usually are in big cities and areas outside of cities. The last two digits of a three-digit Interstate are always the number of the route it is related to. If the first digit is ''odd'' (1, 3, 5, 7, or 9), the Interstate is usually a [[spur route]