The downtown loop, also nicknamed the "Alphabet Loop", is a complex layout of highways in downtown Kansas City, Missouri involving 23 exits, four Interstate Highways, four U.S. Highways and numerous city streets. Each exit in the highway loop is numbered 2 and suffixed with every letter of the alphabet except I, O and Z (I and O would look like 1 and 0 on the exit signs, and Z is not needed), although some of the exits are currently under construction/renovation and closed to traffic.