K Street is a major thoroughfare in the United States capital of Washington, D.C., known as a center for lobbying and the location of numerous advocacy groups, law firms, trade associations, and think tanks.

K Street provides a major east–west thoroughfare for traffic through Washington, primarily from Mount Vernon Square to the Whitehurst Freeway.

[4] The Washington Metropolitan Area Transit Authority has been studying the conversion of K Street into part of a proposed busway.

[8][9] Many of the major D.C.-based lobbying firms were located on the section in Northwest Washington which passes from Georgetown through a portion of downtown D.C., although the strip has grown less popular for lobbyists in recent years.

[10] The major lobbying firms that physically remain on K Street, as of 2017, include CGCN Group and K&L Gates;[11] although smaller and midsized lobbying and advocacy groups as well as law firms, trade associations, some think tanks, and members of the public affairs industry who commonly interact with each other still occupy spaces on K Street and adjacent areas of Downtown Washington, D.C.