The Loop (CTA)

The Loop (historically Union Loop, or commonly Loop) is the long circuit of elevated railroad that forms the hub of the Chicago "L" system in Chicago, Illinois.
As of 2012, the branch has served 74,651 passengers every weekday.
The Loop is so named because the railroad loops around a rectangle formed by Lake Street (north side), Wabash Avenue (east), Van Buren Street (south), and Wells Street (west). The railroad loop has given its name to Chicago's downtown, which is known as the Loop. However, transportation historian Bruce Moffat has concluded that "The Loop" was not used as a proper noun until after Charles Yerkes' 1895–97 construction of the elevated structure.