Chronicling the inception, development, and construction of the New York City subway system
The Interborough Rapid Transit Subway, or IRT, was the first subway company in New York City. Even with elevated train lines springing up around the city, the need for an underground rapid transit railroad was obvious as a solution to street congestion and to assist development in outlying areas. On October 27, 1904, the first IRT subway line opened, and the city would never be the same.
Read More at nycsubway.org
Museum of the City of New York
Wikipedia New York City Subway
History.com New York City subway opens
NY Public Library Subway Construction: Then and Now
The History and Future of the New York Subways
New York City Subway System - Historical Look from 1904
History of the New York City Subway
The New York City Subway: An Express History Tour