The last flight was designated Delta 1965 in honor of the year that the first DC-9 model began flying for the company. McDonnell-Douglas built the last DC-9 in 1982, more than 30 years ago.
Even as other airlines retired their DC-9s, Delta kept the model in service after inheriting a large fleet of the passenger planes in its merger with Northwest Airlines.
The DC-9 is recognizable because of its distinctive T-tail design. But the McDonnell-Douglas MD-80 series, MD-90 and the Boeing 717 are all based on the design of the DC-9, and many of those models are still airborne.
It’s possible that the airline will still use the DC-9 as a substitute for planes that are out of service for repairs.