The 737 is the best-selling jet airliner in history. Boeing has never stopped making 737s since 1967. 7,283 aircraft have been delivered, and the 737 still has 2,759 orders that have not been delivered yet (). Boeing 737s are built at the Boeing Renton Factory in Renton, Washington. The 737's main rival is the Airbus A320 family. On average, 1,250 737s are in the air at any time and two land or leave somewhere every five seconds.