(CNN) -- Nearly half a century after it became the first U.S. airline to fly twin-engine DC-9s, Delta Air Lines retired the last of those venerable airliners from its commercial service Monday.
The final round trip bore the designation Delta 1965 -- the first year the model entered service -- on its way from Atlanta to Minneapolis, and Delta 2014 on the return flight. Delta was the last major U.S. carrier to fly the DC-9, the company said.
Delta had retired its original DC-9s in 1993, but acquired others in its merger with Northwest Airlines in 2008, the company said.
McDonnell-Douglas, which merged with Boeing in 1997, built the last of the T-tail aircraft in 1982. The DC-9 has been replaced by similar-looking successor models such as the MD-88 and Boeing 717 since then.