Which railway was the first to use electric traction for mainline passenger trains in the US?

The Baltimore and Ohio Railroad was the first railway to use electric traction for mainline passenger trains in the United States.

The breakthrough came in Baltimore in 1895 on the B&O’s Baltimore Belt Line. Electric locomotives hauled passenger and freight trains through the Howard Street Tunnel, where smoke from steam locomotives created a serious ventilation problem. Demonstrations began on June 27, and commercial operation followed on July 1.

The system used powerful General Electric locomotives and a 600-volt direct-current supply delivered through an overhead contact arrangement. The electric engines were built for demanding mainline work rather than ordinary streetcar service, making the project an important early test of heavy-rail electrification.

The New York, New Haven and Hartford Railroad is sometimes cited in nearby “first electric train” claims because it began regular electric passenger service on a branch in June 1895. The B&O distinction is specifically its pioneering mainline passenger-and-freight operation, not the first electric railway of any kind.