American railroad on Long Island, N.Y., and one of the few in the world still operating under its original name. Incorporated in 1834, it opened its main line to Greenport, at the eastern end of Long Island, in 1844. Over the years it acquired other Long Island railroads: the North Shore Branch in 1921, a line to Rockaway Beach in 1922, the New York, Brooklyn, and Manhattan Beach Railway in 1925, and the Glendale and East River Railroad in 1928.

Early in the century the Pennsylvania Railroad Company gained control of the Long Island, and it operated out of Pennsylvania Station in Manhattan. In 1966 the Pennsylvania sold it to the state of New York, and since 1968 it has been run by the state's Metropolitan Transportation Authority (MTA).

The railroad has the distinction of having a number of railway firsts: the first railroad in the world to operate a steel-car fleet (1905), the first to discard all wooden passenger equipment (1927), and the first steam road to make practical use of electricity for power (1905). It also is the only American railroad in its class the passenger revenue of which exceeds its freight revenue.