Boeing 377 in 1950 and the first order for the 707 in 1955, Boeing was shut out of the commercial aircraft market. In the mid-1950s technology had advanced significantly, which gave Boeing the opportunity to develop and manufacture new products. One of the first was the guided short-range missile used to intercept enemy aircraft. By that time the Cold War had become a fact of life, and Boeing used its short-range missile technology to develop and build an intercontinental missile. In 1958, Boeing began delivery of its 707, the United States' first commercial jet airliner, in response to the British De
Boeing 707 the McDonnell Douglas MD-95 to Boeing 717 after the company was merged with Boeing. Boeing's customer codes used to identify specific options and livery specified by customers was started with the 707, and has been maintained through all Boeing's models. In essence the same system as used on the earlier Boeing 377, the code consisted of two digits affixed to the model number to identify the specific aircraft version. For example, Pan American World Airways was assigned code "21". Thus, a 707-320B sold to Pan Am had the model number 707-321B. The number remained constant as further aircraft were purchased;