The Independent Subway System, also called 'The Independent' or the IND, was the portion of the New York City subway
built by the city in the early 30s. Until that point, subway and elevated system construction
in the city had been done by private companies
. The previous expansion of the system, in the late teens and early 20s, was contracted out by the city to the two remaining companies which had consolidated the others, the Interboro Rapid Transit
(IRT) and the Brooklyn Rapid Transit (BRT), soon to become the Brooklyn Manhattan Transit
(BMT). However, the city, prompted by mayor John Hyland, who was a disgruntled former employee of the BRT, decided to this time build a competing system with the idea of forcing the two private systems into bankruptcy
and allowing the city to assume all operations. For this reason, the IND system was in several places built very close to existing IRT and BMT lines.
The IND featured what at the time was the cutting edge1 in cut-and-cover tunneling technology. Construction proceeded very rapidly, and by 1932 the first of the lines opened (the current A Train in Manhattan.) Other parts completed shortly thereafter were the 6th avenue trunk line (Part of today's F Train, the Queens Boulevard line to 179th street (home to part several of today's lines including the E and R Trains), the Concourse line in the Bronx (currently served by the B Train), and the Brooklyn/Queens crosstown line (today's G train). One reason construction moved so fast was that the IND lines, in contrast to the IRT and BMT built a decade or more before, didn't feature elaborate or intricate work in the stations, and opted for simple tile.
There were further ambitious plans to extend the IND system which were cut short by the depression and the war. The most famous of these almost subway lines is the Second Avenue line, which may be built yet. Provisions for these additional lines were made in several places.
The IRT and BMT did not fare well and finally the city was able to buy out those companies in 1940, uniting all of the subway and elevated lines under one agency. The new city transit agency went about consolidating the various lines, and making both track and transfer connections between the formerly separate systems. The IND crosstown line was connected to the BMT Culver line, the BMT tunnels were connected to the Queens Boulevard line, and stations of all three systems were connected by passageways. The three system distinction remained though, until 1967, when the Chrystie Street connection from the Manhattan Bridge to the Sixth avenue line was completed and the lines of the IND and BMT were sufficiently intermixed to make division irrelevant. Currently the Metropolitan Transportation Authority operates all of the lines of the New York City subway.
yes, this is a pun