The $787 billion federal stimulus is starting to have a positive effect on construction jobs, the Associated General Contractors of America said.

Stimulus funding along with the growing demand for single-family construction helped boost monthly construction employment in 29 states between March and April. However, 46 states and Washington, D.C., lost construction jobs over the past 12 months.

“A gradual turnaround appears to be taking hold after years of construction employment declines,” said Ken Simonson, the association’s chief economist. “As more stimulus projects get under way and single-family housing starts pick up, we are likely to see the number of states with year-over-year increases grow.”

Seasonally adjusted construction employment from March to April decreased in 18 states and held steady in three, plus Washington, D.C., Simonson said, adding that 17 of the states with monthly increases also added construction jobs from February to March.

“It is encouraging that a solid majority of states added construction jobs in April and that more states are reporting back-to-back monthly gains,” he said.

Kansas experienced the highest monthly increase in construction employment at 8.7 percent. North Dakota, Wyoming, Oklahoma and Massachusetts all experienced an increase in construction jobs. Maine saw the highest monthly decline with 7.7 percent followed by Vermont, Rhode Island, Hawaii and South Carolina.

Simonson noted that the number of states with year-over-year job gains rose to four, led by a jump of 8.1 percent, or 1,300 jobs, in North Dakota. Contractors also added jobs from April 2009 to April 2010 in Kansas, which added 3,800 jobs; Alaska, with a gain of 100 jobs; and Arkansas, with 200 jobs.

The largest numbers of construction job losses were in California, Texas and Florida.

Simonson cautioned that the slump is far from over, citing high building vacancy rates, delays in passing highway and other infrastructure legislation, and declining state and local tax revenue.

“Aside from temporary stimulus projects and a fragile housing market, demand for new construction remains depressed for the foreseeable future,” he said. “As a result, construction employment won’t return to pre-downturn levels for many months.”