Brooklyn-Manhattan Transit Company

Commuter railroad service in Brooklyn dates to 1834 and the founding of the Long Island Railroad (LIRR) during that year. Originally conceived as a means to connect Brooklyn to Boston, Massachusetts more directly, the LIRR played a significant role in the development and economic growth of Long Island's suburban communities, particularly after the railroad was directly linked to Manhattan in the 1880s. As of 2010, the LIRR is the largest and busiest commuter railroad in the United States, with tracks spanning from Penn Station in Manhattan to the far eastern reaches of Long Island, and a daily ridership of over 200,000 commuters.

The Interborough Rapid Transit Company (IRT) began construction of the first subway line in New York City in 1900. In 1909, construction began on Brooklyn's first subway line, the 4th Avenue subway. To encourage the rapid growth of subway construction, in 1913 the City of New York divided the disbursement of contracts between two companies: the IRT and the Brooklyn Rapid Transit Company (BRT), which was later renamed the Brooklyn-Manhattan Transit Corporation (BMT). Under the "dual contract" system, the IRT was awarded rights to expand the existing Manhattan, Brooklyn, and Bronx lines, while the BMT was awarded contracts for the construction of new lines in Manhattan, Brooklyn, and Queens. In the 1920s, the city-owned Independent Subway System (IND) was established to further expand the capacity of the city's subway system, as well as to compete with the privately-owned IRT and BMT. The IND's first completed line, the Eighth Avenue subway, opened in 1932.

In 1940, the IRT and BMT were acquired by the city and all three lines were consolidated with the IND into the New York City Board of Transportation. In 1953, the New York City Transit Authority (NYCTA) was established as a public benefit corporation to operate the subway system, and in 1968 the NYCTA was placed under the control of the Metropolitan Transit Authority, which continues to oversee and operate New York City's subway system as of 2010.