In 2001, Boeing began implementing a moving assembly line for production of the 717 and 737. The moving line greatly reduced production time, which led to lower production costs. Following the slump in airline traffic caused by an economic downturn subsequent to the terrorist attacks on September 11, 2001, Boeing announced a review of the type's future. After much deliberation, it was decided to continue with production. Despite the lack of orders, Boeing had confidence in the 717's fundamental suitability to the 100-seat market, and in the long-term size of that market. After 19 worldwide 717 sales in 2000, and just 6 in 2001, Boeing took 32 orders for the 717 in 2002, despite the severe industry downturn. The 100th 717 was delivered to AirTran Airways on June 18, 2002.