The Nassau Electric Railroad was an electric street railway company in the U.S. state of New York. The company operated throughout the borough of Brooklyn, as well as over the Brooklyn Bridge and Williamsburg Bridge into Manhattan.

The Atlantic Avenue Railroad was a company in the U.S. state of New York, with a main line connecting downtown Brooklyn with Jamaica along Atlantic Avenue. It was largely a streetcar company that operated its own trains, but the Long Island Rail Road operated both streetcars and steam trains over its main line. It later became part of the Nassau Electric Railroad, but is now divided between the active Atlantic Branch of the LIRR and the unused Cobble Hill Tunnel, which is preserved in its original state, albeit without service tracks.