Query: When did Boeing move its headquarters to Chicago?
Context: Seattle remained the corporate headquarters of Boeing until 2001, when the company separated its headquarters from its major production facilities; the headquarters were moved to Chicago. The Seattle area is still home to Boeing's Renton narrow-body plant (where the 707, 720, 727, and 757 were assembled, and the 737 is assembled today) and Everett wide-body plant (assembly plant for the 747, 767, 777, and 787).