But another reason vacancy rates are so low is because supply isn't keeping up with demand. While a limited number of new apartments are under construction in pockets like Royal Oak, Ferndale, Milford and Plymouth, the pace of new apartment development in the metro Detroit area may lag behind other regions, said Samuel Beznos, CEO of Farmington Hills-based Beztak Cos.

"We had 10 plus years of downturn, and it could have arguably been more. There is very little construction," said Beznos.

"The articles recently about Detroit, with 2,000 units coming to the city — other metros could have had 20,000," Beznos said. Beztak has a 17,000-unit multifamily portfolio under ownership and management, with 12,000 of those units in Michigan.

Rents have also been rising substantially, which could spur new construction. This year, 2,600 apartments are expected to come online, up from 2,400 in 2016 and 1,500 in 2015, according to Marcus & Millichap. Rents are expected to rise 5.7 percent this year to $951 and rose 5.7 percent last year to $910 per month, according to Marcus & Millichap.

Marcus & Millichap is not the only firm that gives metro Detroit strong marks for its multifamily market. Berkadia, which is based in Ambler, Pa., and has an office in Southfield, predicts the vacancy rate will remain steady at 3.4 percent and expects a 3.5 percent rent increase to $1,005 per month by the end of the year.

Kevin Dillon, managing director of Berkadia's Southfield office, said he expects rents to continue to rise overall between 3 and 6 percent through 2018 and, barring a downturn, multifamily occupancy rates to remain above 95 percent.

The strong rent and vacancy numbers have fueled some large local apartment complex sales in recent years, including some of the largest, in terms of total cost.

Two of the top five investment sales in 2016 were for big apartment buildings, including the $79.5 million purchase of the Riverfront Towers in downtown Detroit and the $32.25 million purchase of the Fairlane East apartments in Dearborn. Riverfront Towers has 557 apartments ($142,729 per unit), while Fairlane East has 244 ($128,074 per unit). Both sold to out-of-state investors.

In 2015, the largest sale of the year was 2,226-unit Somerset Park Apartments in Troy for $216 million; Cedarbrooke Apartments in Auburn Hills sold for $49 million for its 584 units.

Those also sold to out-of-state investors.