Auto parts supplier Flex-N-Gate's construction of a 500,000-square-foot manufacturing plant on 30 vacant acres of east side Detroit land highlights a growing dilemma for bringing industrial jobs back to the Motor City.

Detroit's burgeoning 186-acre I-94 Industrial Park north of the I-75 and I-94 interchange is almost full with the arrival of Flex-N-Gate and ArcelorMittal Tailored Blanks, another auto parts supplier that's building a 317,000-square-foot facility.

"We're almost out of land," Mayor Mike Duggan said Monday.

The mayor's statement almost seems impossible to believe in a city that's torn down 11,227 vacant homes since Duggan took office in 2014.

But assembling contiguous tracts of vacant land with access to Detroit's interstate highways is growing increasingly difficult for city planners.

"There aren't that many," Duggan said. "So we're working on creating more of them."

The biggest tract of land the Duggan administration is eying is the 264-acre Coleman A. Young International Airport (formerly called the Detroit City Airport), which has fewer than eight departures on an average day and can't break even every year without taxpayer financial support.

The mayor's team recently issued a request for proposals from real estate developers on whether the airport could be shut down and redeveloped for increased economic activity.

There's several blocks of nearly vacant residential parcels west of the airport and French Road that could be assembled along with the airport for development of another industrial park or an autonomous vehicle testing park.

"The airport needs to be analyzed," Duggan said.

The airport also has a caucus, of sorts, on City Council that will fight Duggan if he attempts to close it.

The City Council has passed resolutions in recent years calling for more taxpayer investment in the facility to lure a commercial airliner back to the city after a 18-year hiatus.

Duggan, a numbers guy, contrasted the number of people working at the city airport with the 400-plus employees Flex-N-Gate owner Shahid Khan will employ at his new plant when it begins producing parts for Ford Motor Co. a year from now.

"You've got 300 acres of land that right now has 200 people employed," Duggan said of the airport. "Shahid Khan is going to employ 400 to 700 in 30 acres. So you have to evaluate all of your options — and that's all we're doing."

Chad Livengood: (313) 446-1654

Twitter: @ChadLivengood