First Electric Multiple Unit Service

On May 19, 1903, the Boston Elevated Railway launched electric multiple unit (EMU) operations on its elevated lines, a pioneering step in subway and streetcar evolution. This innovation allowed trains to operate without a separate locomotive, improving efficiency and acceleration in dense city environments. Engineers drew from emerging AC/DC systems, addressing challenges like power distribution and braking on steel structures. The EMUs facilitated rapid growth of Boston's rapid transit, reducing reliance on steam and horses, and set precedents for systems worldwide including New York and London subways, enhancing urban mobility during the Progressive Era.