Richard W. Longstreth (born 4 March 1946, Pasadena) is an architectural historian and a professor at George Washington University where he directs the program in historic preservation.
His early scholarly work focused on the late nineteenth century architects of the San Francisco Bay Area and led to his book On the Edge of the World: Four Architects in San Francisco at the Turn of the Century (1983), but more recently he has focused on architecture in relationship to the decentralization of American cities.
His book, City Center to Regional Mall: Architecture, the Automobile, and Retailing in Los Angeles, 1920–1950, won the 1997 Abbott Lowell Cummings Award from the Vernacular Architecture Forum, the 1997 Lewis Mumford Prize of the Society for American City and Regional Planning History, and the 1999 Spiro Kostof Award of the Society of Architectural Historians.
He has chaired the Maryland Governor's Consulting Committee on the National Register of Historic Places.
He was first vice president of the Vernacular Architecture Forum in 1989-91, has been a trustee of the National Building Museum, and has served as a board member of Preservation Action.