on Fulton, where it ran over the Brooklyn City Rail Road's Fulton Street Line to Troy Avenue, and continued south on Troy to end at Bergen Street. The Broadway Railroad leased the line on December 31, 1881. The Brooklyn, Queens County and Suburban Railroad, owned by the Long Island Traction Company (later the Brooklyn Rapid Transit Company or BRT), leased the Broadway Railroad in early 1894, and the line was electrified in late October. The BRT would become the Brooklyn–Manhattan Transit Corporation (BMT) in 1923. Conversion to bus service 20th century Beginning in the 1920s many streetcar lines in Brooklyn and the rest of the city began to be replaced by buses, particularly after the unification of the city's three primary transit companies (including the BMT) under municipal operations in June 1940. The New Lots Avenue Line was converted to buses in mid-1941, running from the Canarsie Depot at Rockaway Avenue and Hegeman Avenue continuing east along Hegeman Avenue and Linden Boulevard to Atkins Avenue/Berriman Street in East New York. The service was assigned the B10 designation. On July 8, 1947, the B10 was extended to replace Sumner Avenue trolley service. The Sumner route was cut back from Williamsburg Bridge Plaza to its current terminal at Broadway and Sumner Avenue with direct Bedford–Stuyvesant-Red Hook service unreplaced. Sumner trolley service was fully eliminated in 1949. On September 29, 1963, several Brooklyn streets including Sumner Avenue were turned into one-way streets; Sumner Avenue would become southbound only. Northbound B10 buses were rerouted onto Lewis Avenue at this time. By this time, the B10 had been extended east along Linden Boulevard to Drew Street/Elderts Lane in New Lots/Spring Creek, near the Brooklyn-Queens border. This extension had been proposed around 1960 to serve the Cypress Hills and Louis Heaton Pink public housing complexes in New Lots. The bus would serve Brooklyn General Mail Facility in Spring Creek when it opened in 1991. In 1993, the route was extended to its current terminal at John F. Kennedy International Airport's Terminal 4 in Jamaica, Queens. When the route was extended to Kennedy Airport it was redesignated as the B15 (the previous designation for a route between City Hall and Downtown Brooklyn) to avoid confusion with the , an existing route serving the airport, at the time operated by Green Bus Lines (now part of MTA Bus Company). 21st century On April 11, 2004, 24-hour service was