The Rock Creek Railway was one of the first electric streetcar companies in Washington, D.C. It was incorporated in 1888 and started operations in 1890. After expansion, the line ran from the Cardoza/Shaw neighborhood of D.C. to Chevy Chase Lake, Maryland. On September 21, 1895, Rock Creek Railway purchased the Washington and Georgetown Railroad Company and the two formed the Capital Traction Company.
The Rock Creek Railway was incorporated by Francis Newlands on June 23, 1888 — four days after the Eckington and Soldiers' Home Electric Railway was chartered. In 1890, service began on Florida Avenue between Connecticut Avenue NW and 18th Street NW. The company built an iron bridge across Rock Creek at Cincinnati Street NW (now Calvert Street NW), which was completed on July 21, 1891. On September 16, 1892 the line was extended up 18th Street to the neighborhood now known as Adams Morgan, across the Cincinnati Street Bridge and northward on Connecticut Avenue NW all the way to the District Line. The company also acquired trackage built by the Chevy Chase Land Company, extending the line to Chevy Chase Lake, Maryland. Along the way it connected to the Metropolitan Railroad's Connecticut Avenue Line, and to the power house at the crossing of the Georgetown Branch of the Baltimore and Ohio Railroad in Chevy Chase. Power was supplied by an overhead trolley wire.
Extensions east on Florida Avenue to North Capitol Street, and north to the National Zoo, were authorized on April 30, 1892, but never built.