The Loop (CTA)

The Loop
The southeastern corner of The Loop
Overview
Type	Rapid transit
System	Chicago "L"
Status	Operational
Locale	Chicago, Illinois, USA
Stations	8
Services	Orange Line      Green Line      Purple Line weekday rush hours only      Brown Line      Pink Line
Daily ridership	74,651 (average weekday 2012)
Operation
Opened	1895–1897
Operator(s)	Chicago Transit Authority
Character	Elevated
Technical
Track length	1.79 miles (2.9 km)
Number of tracks	2
Track gauge	4 ft 8 1⁄2 in (1,435 mm) standard gauge
Minimum radius	90 feet (27 m)
Electrification	Third rail, 600v DC
Route map  Diagram    Clark/Lake Fifth / Lake State / Lake Randolph / Wells Randolph / Wabash Washington / Wells Madison / Wells Madison / Wabash Adams / Wabash Quincy LaSalle / Van Buren Library Dearborn/Van Buren

The Loop (historically Union Loop, or commonly Loop) is the 1.79-mile (2.88 km) 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. Numerous accounts assert that the use of this term predates the elevated railroad, deriving from the multiple cable car turntables, or loops, that terminated in the district, and especially those of two lines that shared a loop, constructed in 1882, bounded by Madison, Wabash, State, and Lake. 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.

The Loop includes eight stations: Clark/Lake and State/Lake are on the northern leg; Randolph/Wabash and Adams/Wabash are on the eastern side; Library and LaSalle/Van Buren are on the southern leg; and Quincy and Washington/Wells are on the western side. In 2011 20,896,612 passengers entered the 'L' via these stations.

Five of the eight 'L' lines use the Loop tracks. Two of the remaining three lines, Blue Line and Red Line, run underground through the center of the loop, connecting to Loop stations. The Yellow Line is the only CTA line that does not run on or connect to the loop. The Purple Line Express (weekday rush hours only) and the Brown Line enter from the north at the northwestern corner. The Purple Line Express makes a full circuit in the clockwise direction while the Brown Line makes a full circuit traveling counterclockwise. The Orange Line enters from the south at the southeastern corner and the Pink Line enters from the west at the northwestern corner; both making a full clockwise circuit. Following the completion of a full circuit in their directions, trains of these four lines return to their terminals making stops in the reverse order they made when heading to the Loop. The Green Line runs in both directions but does not make a full circuit, using only the north and eastern sides of the Loop to move between the Lake Street branch and the South Side Elevated.