Early history of the IRT subway

The first regularly operated subway in New York City was built by the city and leased to the Interborough Rapid Transit Company for operation under Contracts 1 and 2 of the Dual Contracts. Until 1918, when the new "H" system that is still operated - with separate East Side and West Side lines - was placed in service, it consisted of a single trunk line below 96th Street with several northern branches. The system had four tracks between Brooklyn Bridge – City Hall and 96th Street, allowing for local and express service on that portion. Under the "H" system, the original line and early extensions are now as follows:

• The IRT Eastern Parkway Line from Atlantic Avenue – Barclays Center to Borough Hall
• The IRT Lexington Avenue Line from Borough Hall to Grand Central – 42nd Street
• The IRT 42nd Street Shuttle from Grand Central – 42nd Street to Times Square
• The IRT Broadway – Seventh Avenue Line from Times Square to Van Cortlandt Park – 242nd Street
• The IRT Lenox Avenue Line from 96th Street to 145th Street
• The IRT White Plains Road Line from 142nd Street Junction to 180th Street – Bronx Park (removed north of 179th Street)