The end has come for the American Airlines’ overhaul base at Kansas City International Airport.

A maintenance base that once boasted 6,000 high-paying jobs has been closed. The overhaul base hit its high point in the 70s when it was run by TWA. American kept it open for nine more years when it bought TWA in 2001, but the workforce dropped over the years, falling to a low of 450. Kansas City will be shopping the base to potential new owners, looking to revive employment at the 7 million-square-foot base.