L.A. County’s unemployment rate edged up two tenths of a point in July to 12.4 percent as the county was hit by the triple whammy of seasonal job losses in education, the winding down of the federal census and cutbacks in state and local government.

The July unemployment rate was slightly higher than the statewide rate of 12.3 percent and significantly higher than the 9.5 percent nationwide average. L.A. County’s unemployment rate stood at 12.2 percent in June and 11.9 percent a year ago.

The county saw a drop of 37,400 non-farm payroll jobs in July, with two thirds of those losses occurring in education as thousands of teachers were on summer break or had been given pink slips due to tight school budgets.

Adding to the misery were the layoffs of several thousand temporary federal census workers as the decennial census wound down. And state and local government payrolls shrank as the new fiscal year began with governments trying to plug gaping deficits.

However, when adjusting for seasonal factors, the county lost only 2,400 jobs, according to Beacon Economics, a Los Angeles economic consulting company.

One of the few bright spots in was construction, which gained nearly 2,000 jobs. More than half of the gain was in heavy construction associated with public works projects. The increase could signal a rebound from the sector’s three-year slump as the region’s housing market collapsed.

Meanwhile, there was some encouraging news in the closely-watched year-over-year jobs figures. L.A. County’s non-farm employment fell by only 23,500 jobs between July 2009 and July 2010, a drop of 0.62 percent.

The biggest year-over-year jobs increase was in the motion picture industry, which added nearly 22,000 jobs. But drops in government, manufacturing and construction jobs more than offset this gain.

L.A. County’s two largest cities, Los Angeles and Long Beach, posted jobless rates of 14.7 percent and 14.6 percent respectively.