Orange County job-seekers poured into the market last month in the wake of high school and college graduations, boosting the size of the county’s labor force — but also its unemployment rate.

Joblessness ticked up to 3.8 percent from 3.1 percent in May, a rise that reflected a larger number of people looking for work.

However, while the county saw a seasonal jump of 6,000 net new jobs last month, for a total of 1,594,900, its year-over-year payroll growth stood at a modest 1.2 percent — a rise of 19,000 positions.

“Orange County’s economy has slowed quite a bit,” said Christopher Thornberg, a founder of Beacon Economics, a Southern California research firm. “Last year, the county added 36,000 jobs from June to June, and the year before it was 47,000.”

California is also seeing “a big slowdown,” he added. “In the past, we’ve been able to grow on the job front because there was an excess supply of workers. That is gone. Last year, the state added 150,000 jobs from December to June. This year, we are at 65,000.”

Last month, California actually lost 1,400 jobs while year-over-year payrolls grew 1.6 percent. The state’s jobless rate was 4.7 percent, the same as in May.

The U.S. unemployment rate stood at 4.4 percent in June.

Thornberg and other experts place much of the blame for slowing growth on California’s severe housing shortage. High prices, due to a lack of supply, are discouraging workers from moving to the state and are spurring businesses to expand elsewhere to find employees, they say.

“In Orange County and in California, we are in a tight labor market and it is only getting tighter,” said Genine Wilson, a regional vice president at the staffing firm Kelly Services.

“There are more job openings than there are employees. The challenge for employers is to find qualified talent, given the cost of living. Employers are not paying enough to attract skilled workers to Orange County.”

Mid-tier positions are particularly hard to fill, she added. “It is difficult to relocate someone from Florida, say, where they can live comfortably in a three-bedroom house, as opposed to living in a one-bedroom apartment here.”

Here are year-over-year trends within the county’s major job sectors:

–Professional and business services grew to 300,900, adding 8,200 positions, the most of any category. But more than 90 percent of the jobs were in administrative and support services, including temporary workers.

–Leisure and hospitality, including positions at hotels and restaurants, grew to 218,600, with 3,300 more jobs.

–Healthcare and social services employed 177,000, a loss of 300 jobs.

–Government jobs grew to 164,100, with an increase of 1,200, mostly public school teachers.

–Manufacturing declined to 153,700, with a loss of 1,800 jobs as companies continued to automate and move operations to less expensive labor markets.

–Retail jobs dropped to 148,300, with a loss of 1,400 positions, as the growth of online shopping led to the closing of brick-and-mortar stores.

–Construction grew to 100,700, adding 4,300 jobs, mostly in specialty trades.

–Financial activities grew by 600 jobs to 117,300.