EVERETT — Snohomish County’s jobless rate rose slightly in May to 7.9 percent but was down from 9.2 percent in May 2011.

The county’s unemployment rate increased 0.8 percentage points from April’s revised rate of 7.1 percent, according to a report released Tuesday by the state Employment Security Department.

“It is not uncommon to see an upward shift in the unemployment rate between April and May each year,” said regional labor economist Annelise Vance-Sherman of the department’s Everett office. “One of the factors that contributes to the rising unemployment rate at this time of year is entry of youth into the labor force, in search of summer employment.”

About 30,760 people were unemployed in the county last month, up from 27,580 in April. However, there were 35,490 jobless people in the county in May 2011.

Year-over-year, employment in the county’s non-durable goods industry is down nearly 16 percent, shedding about 600 positions since May a year ago. The industry was down another 100 jobs last month to 3,200 positions from April.

Also hard-hit in the recession was the county’s construction industry. Construction, however, added about 200 jobs in May. Between the construction of buildings and civil engineering, employment in the county’s construction sector is up more than 5 percent over May 2011.

Aerospace continues to lead year-over-year job growth, adding 100 jobs in May as the Boeing Co. and its suppliers increased production. Employment in the industry is up 12.5 percent since May 2011, having added 4,900 jobs over the year.

“Manufacturing employment has propelled Snohomish County throughout this period of recovery,” Vance-Sherman said in her analysis of the employment data. “Over the past several months, the rate of new job creation in manufacturing has begun to flatten out. Modest over-the-month job growth in aerospace was cancelled out by job losses from wood product and nondurable goods manufacturing.”

Total non-farm employment expanded by 800 between April and May, continuing a trend of rising job counts over the past couple years. Sectors posting gains include retail with 400 jobs; construction, 300; leisure and hospitality, 300; transportation, warehousing and utilities, 100; information services, 100; and other services, 100. Sectors losing jobs include government, down 300 jobs; manufacturing, down 100; and professional services, down 100.

Over the year, total non-farm employment in Snohomish County increased by 8,700, or 3.5 percent. The private sector has been responsible for most job growth. The manufacturing industry created the largest number of jobs in Snohomish County over the year. This sector added an estimated 4,400 jobs to the local economy, increasing payrolls by 7.7 percent between May 2011 and May 2012.

In April, the Kimberly-Clark paper manufacturing facility in Everett was officially closed. More than 700 workers were laid off between December and April. The statewide report (www.esd.wa.gov/employmentdata) indicates a loss of 200 jobs from the Washington’s paper manufacturing industry over the month and 700 over the year. At the Snohomish County level, paper manufacturing is aggregated with other non-durable goods manufacturing. This month, non-durable goods in the county dropped by 100 and reflected a year-over-year loss of 600.

Retail trade has been a notable growth engine for jobs, both over the month and over the year, Vance-Sherman said. For the most part, growth in retail trade in Snohomish County has been concentrated in general merchandise stores, with recent growth in food and beverage stores. Over the year, retailers contributed 1,700 jobs to the local economy, growing their workforce by 5.6 percent.