YORK SUBWAY HISTORY
The New York
subway was originally built as three separate subway systems.
Rapid Transit or IRT was the first of these subway systems to open,
following more than twenty years of public debate on the merits
of subways versus the existing elevated rail system and on various
proposed routes. It opened on October 27, 1904. The first IRT line
to open ran between City Hall and Broadway and 145th Street.
Transit or BMT operated both elevated trains (els) and subways,
mostly within Brooklyn or connecting Brooklyn to Manhattan and Queens.
It was originally called the Brooklyn Rapid Transit Company but
was renamed in 1923.
Subway System or IND first opened in 1932, as a municipally-owned
alternate to the two earlier private systems. The first IND line
to open was the 8th Avenue line.
The three lines
were unified and then operated by the New York City Transit Authority
(now MTA New York City Transit) in 1940. However, the distinction
between the three systems survives in the line numbering: IRT lines
have numbers, BMT/IND letters. There's also a more physical but
less obvious difference. IRT cars and tunnels are narrower than
BMT and IND ones. Neither BMT nor IND cars can fit into IRT tunnels
due to dangerously narrow clearances. IRT cars can travel on BMT/IND
lines when necessary, but are not used for passenger service on
those lines due to the dangerously wide gap between the car and
the station platform.