Although the Washington City Canal remained in use after the coming of the railroad, by 1855 it had filled with silt and debris to the point where it was no longer functional. It remained in this condition throughout the 1860s. In 1871, Congress abolished the elected mayor and bicameral legislature of the District of Columbia, and established a territorial government. Territorial government only lasted until 1874 (at which time Congress imposed an appointed three-member commission on the city), but during this period the D.C. Board of Public Works enclosed the canal and turned it into a sewer. B Street NW from 15th Street to Virginia Avenue NW was constructed on top of it. Work began in October 1871 and was complete in December 1873.