While 39 states added construction jobs between May 2015 and May 2016, construction employment increased in only 19 states between April and May, according to analysis of Labor Department data by the Associated General Contractors of America. Monthly construction employment levels declined in most states as many firms appear to be running out of workers to hire amid growing labor shortages, according to the association.

“With construction demand remaining high and construction unemployment getting lower, the slowdown in monthly hiring probably has a lot more to do with a lack of workers than it does a lack of work,” says Ken Simonson, chief economist for AGC. “Overall the construction market appears robust and as long as most firms can find qualified workers.”

California added the most construction jobs (39,600 jobs, 5.5 percent) between May 2015 and May 2016. Other states adding a high number of new construction jobs for the past 12 months include Florida (29,400 jobs, 6.9 percent), Georgia (13,400 jobs, 8.1 percent) and New York (11,000 jobs, 3.0 percent). Hawaii added the highest percentage of new construction jobs during the past year (19.7 percent, 6,700 jobs), followed by Iowa (13.4 percent, 10,400 jobs), Nevada (10.1 percent, 6,900 jobs) and Idaho (3,400 jobs, 8.9 percent).

North Dakota lost the highest percent and total number of construction jobs (-10.5 percent, -3,700 jobs). Other states that lost jobs for the year include Kansas (-3,400 jobs, -5.6 percent), Pennsylvania (-2,900 jobs, -1.2 percent), West Virginia (-2,700 jobs, -8.0 percent), Alabama (-1,300 jobs, -1.6 percent) and Wyoming (-1,200 jobs, -15.2 percent).

New Jersey added the most construction jobs between April and May (2,900 jobs, 1.9 percent). Other states adding a high number of construction jobs include Florida (2,500 jobs, 0.6 percent), Oklahoma (1,800 jobs, 2.2 percent), Virginia (1,700 jobs, 0.9 percent) and Washington (1,600 jobs, 0.9 percent). Oklahoma added the highest percentage of construction jobs during the past month, followed by New Jersey, Alaska (1.8 percent, 300 jobs) and Hawaii (1.8 percent, 700 jobs).

Construction employment declined in 30 states and D.C. during the past month and held steady in Indiana. Texas shed more construction jobs than any other state (-3,400 jobs, -0.5 percent), followed by Wisconsin (-3,200 jobs, -2.7 percent), Pennsylvania (-2,900 jobs, -1.2 percent) and California (-2,800 jobs, -0.4 percent). Vermont lost the highest percentage of construction jobs between April and May (-6.1 percent, -1,000 jobs), followed by West Virginia (-5.8 percent, -1,900 jobs), Wisconsin and Missouri (-2.3 percent, -2,700 jobs).

Association officials say that considering the low overall unemployment rate for the sector and continued strong demand for most types of construction activity, the fact a majority of states lost construction jobs for the month likely occurred because many firms are having a hard time finding qualified workers to hire.

“Now that labor shortages appear to be undermining construction employment, it is only a matter of time before the lack of workers impacts broader economic conditions,” says Stephen E. Sandherr, the association’s CEO. “Public officials need to act now to boost investments in the kind of skills-based education programs that help students succeed in school and land high-paying jobs in fields like construction.”