The construction industry added 48,000 jobs in February, the ninth consecutive month of job growth for the sector, as more people are working in construction than at any point in the last three-and-a-half years, according to an analysis of new government data by the Associated General Contractors of America.

Association officials cautioned, however, that employment gains remain tenuous and could be undermined if Washington officials fail to reach a deal on federal investment levels later this month.

“With construction employment increasing by the largest amount for a single month in nearly six years, the steady improvement in construction hiring is particularly encouraging,” said Ken Simonson, the association's chief economist. “The job gains are coming from every part of the construction industry and while the sector’s unemployment rate remains stubbornly high, it is heading in the right direction.”

Construction firms employed 5.78 million people in February, a gain of 48,000 from January and 140,000 or 2.5% from a year ago, Simonson noted. The industry unemployment rate, which is not seasonally adjusted and thus is typically high in February, fell from 17.1% in February 2012 to 15.7% last month.

Both residential and nonresidential construction added jobs for the month and year. Residential construction—building and specialty trade contractors—added 19,400 jobs in February and 64,200 (3.1%) over 12 months. Nonresidential construction—building, specialty trade, and heavy and civil engineering construction—expanded by 29,000 employees in February and 75,700 (2.1%) over the year-ago level.

“Both single- and multifamily homebuilding have been accelerating for several months and should continue to add jobs in the near future,” Simonson said, noting that he expects construction employment may increase by 250,000 in 2013. “On the private nonresidential side, there will likely be strong growth in power and energy-related projects, manufacturing and distribution facilities and private college construction. However, public construction remains weak.”