Constitution Avenue

Constitution Avenue is a major east–west street in the northwest and northeast quadrants of the city of Washington, D.C., in the United States. It was originally known as B Street, and its western section was greatly lengthened and widened between 1925 and 1933. It received its current name on February 26, 1931, though it was almost named Jefferson Avenue in honor of Thomas Jefferson.

Constitution Avenue's western half defines the northern border of the National Mall and extends from the United States Capitol to the Theodore Roosevelt Bridge. Its eastern half runs through the neighborhoods of Capitol Hill and Hill East before terminating at the RFK Stadium campus. Many federal departmental headquarters, memorials, and museums line Constitution Avenue's western segment.

Creating B Street

When the District of Columbia was founded in 1790, the Potomac River was much wider than it currently is, and a major tidal estuary known as Tiber Creek flowed roughly from 6th Street NW to the shore of the river just south of the White House. In Pierre (Peter) Charles L'Enfant's original plan for the city in 1791, B Street NW began at 6th Street NW, and ended at the river's edge at 15th Street NW. Its eastern segment, which was unimpeded by any water obstacles, ran straight to the Eastern Branch River, now known as the Anacostia River. Along its entire length, B Street was 60 feet (18 m) wide.

L'Enfant proposed turning Tiber Creek into a canal.