First Electric Multiple Unit Service

On May 16, 1903, the Boston Elevated Railway launched regular service with electric multiple-unit (MU) cars on its elevated lines. Designed by Frank Sprague's team, these self-propelled cars eliminated the need for separate locomotives, allowing faster acceleration and higher frequency in dense urban corridors. This innovation reduced operating costs and improved reliability compared to steam or cable systems. The technology quickly spread to New York and Chicago, forming the backbone of modern subway and commuter rail operations globally. Enthusiasts note the distinctive wooden cars and third-rail power collection that defined early 20th-century American rapid transit.