The multifamily construction pipeline has taken a nosedive to numbers that haven’t been seen in a decade and a half, according to Apartments.com and CoStar. 
Roughly 55,000 units broke ground across the U.S. during the first quarter, the lowest quarterly volume since 2011, as higher development and financing costs and a slowdown in rent growth have limited new construction. 
Only about 579,000 units were underway at the end of the quarter, a 50% decline from the 2023 peak and also back to levels last seen in the mid-2010s.
The free fall in starts comes despite a record wave of office-to-residential conversions sparked by a looming…