The B54 operates from MTA New York City Bus's Fresh Pond Depot in Ridgewood, Queens.

Until 1969, the BMT line also ran on elevated tracks above the entire Brooklyn section of Myrtle Avenue.

[1]: 14 Westbound service continues via Myrtle Avenue until Lawrence Street, where buses make a left.

[6] On the second day of the horsecar's operation, a boy was injured while surfing outside one of the vehicles; author Brian Cudahy described this as a “sport” that would soon become quite popular with Brooklyn youth".

[3]: 25–26 The Brooklyn City Railroad had planned to build a system of several horsecar lines across Brooklyn, but was only able to start horsecar service along Myrtle Avenue after buying the operating rights of a stage coach line that had been operated by Seymour L.

[13] The Myrtle Avenue Line was also one of seven that were moved to the new elevated structure on the Brooklyn Bridge on September 28, 1908; the lines accessed the structure using the Sands Street elevated station, on the Brooklyn side of the bridge.

[18] Beginning in the 1920s, many streetcar lines in Queens, 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.

[19] On June 30, 1949, the New York City Board of Estimate approved the full motorization of the Myrtle Avenue and Court Street Line with buses.

[23][24][25] On January 20, 1955, the NYCTA approved a resolution to defer the planned service cuts until after July 1, 1955, pending additional ridership checks.

[35] On July 1, 2007, the travel path of the B54's terminal loop in Downtown Brooklyn was reversed to improve traffic flow and to provide faster service to the Jay Street subway station.

Palmetto Street was closed to all traffic except for New York City Transit buses and deliveries.

[39] The change was possible because the tenant that required the security measures was leaving MetroTech; it was expected to improve reliability and provide faster service to the subway.

[40] In response to declining ridership, the MTA proposed reducing bus frequencies along the B54 route in July 2019,[41] prompting demonstrations from opponents.

[42][43] The changes took effect in September 2019,[44] in spite of riders' complaints that B38 buses were frequently overcrowded even before the service cuts.