Chicago Elevated Terminal Railway Co. - circa 1890's Railway Stock Certificate - Branch Line of the Atchison Topeka Santa Fe Railway

Unissued Stock. This is a Branch Line of the Atchison, Topeka and Santa Fe Railway. The Chicago "L," an abbreviation for "elevated," serves as the rapid transit system for the city of Chicago and several adjacent suburbs in Illinois. Managed by the Chicago Transit Authority (CTA), it ranks as the fourth-largest rapid transit system in the United States by total route length, measuring 102.8 miles (165.4 km) as of 2014. It is also the third-busiest rapid transit system in the country, following the New York City Subway and the Washington Metro. As of January 2024, the "L" operates 1,480 rail cars across eight distinct routes on a total of 224.1 miles of track. The CTA facilitates approximately 1,888 trips daily, serving 146 train stations.

In 2024, the system recorded 127,463,400 rides, averaging about 390,100 rides per weekday in the fourth quarter. The "L" offers 24-hour service on both the Red and Blue Lines, positioning Chicago alongside New York City and Copenhagen as the only cities globally to provide continuous train service on select lines within their city limits. The earliest segments of the Chicago "L" commenced operations in 1892, making it the second-oldest rapid transit system in the Americas, following the elevated lines of New York City. The name "L" derives from "el," reflecting the extensive elevated sections of the system, although parts of the network also operate in subway tunnels, at ground level, or in open cuts.