 Between I-395 and Clarendon, Washington Boulevard was built on the right-of-way of the Washington, Arlington and Falls Church's South Arlington Branch in the late 1920s.The road was completed when the section from I-395 to Memorial Circle was built in the early 1940s.On September 11, 2001, many commuters and drivers witnessed the hijacked American Airlines Flight 77 as it passed directly over Washington Boulevard and crashed into The Pentagon.