SALEM— The unemployment rate in Oregon has dipped below 8 percent for the first time since the nation fell steeply into the Great Recession in the fall of 2008.

The state unemployment rate was 7.8 percent in May and, after a revision, 7.9 percent in April, the state Employment Department said Tuesday.

Job gains have been strong recently in construction as well as in the trade, transportation and utilities sectors, The Oregonian reported.

But manufacturing gained only half the number of jobs expected in May, a subpar performance in a sector that has shown strength during the state’s slow recovery from the recession.

Overall, the state gained 3,800 jobs in May. The statistic is seasonally adjusted.

Economists say that months of such job gains have helped to reduce the unemployment rate.

But, they say, the rate also is falling because the percentage of the population in the labor force is dropping. What’s called “labor force participation” is at a 40-year low in Oregon.

Retiring baby boomers are a significant reason for that.

The percentage of adults in the labor force varies widely statewide. It’s 83.7 percent in Hood River County, and it’s 47.4 percent in the southern coastal retirement center of Curry County — the only county where fewer than one in two adults either works or is looking for work.

Unemployment in Oregon is now just slightly higher than the U.S. average, 7.6 percent.