Boeing 737s serve markets previously filled by several airliners.
Many 737s serve markets previously filled by 707 , 727 , 757 , DC-9 , and MD-80 / MD-90 airliners , and the aircraft currently competes primarily with the Airbus A320 family .	707	Boeing 707	727	Boeing 727	757	Boeing 757	DC-9	DC-9	MD-80	MD-80	MD-90	MD-90	Airbus A320 family	Airbus A320 family
