Setting the scene
New York's elevated trains could not keep pace with a swelling population; city leaders backed a underground rapid transit system to move millions across Manhattan and into the Bronx.
What happened
The New York City subway opened on October 27, 1904, with Mayor George McClellan Jr. at the controls of the first train leaving City Hall station.
Why it still matters
The subway became one of the world's largest rapid-transit systems and the backbone of daily life for millions of commuters. Memorable detail: the ornate City Hall loop station closed to regular service in 1945 but still exists as a ghost platform.
Background
It became one of the world's largest rapid transit systems.