Whatcom County’s unemployment rate last month reached its lowest level in nearly four years.

Unemployment in the county was at 6.4 percent in October, according to preliminary estimates from the state Employment Security Department.

That rate is below a revised 6.9 percent estimate from September 2012, and a 7.4 percent level from October of last year.

The region saw unemployment fall at the same time the workforce added nearly 2,500 people, a combination that labor market economist Elizabeth Court said was “pretty striking.”

A downturn in unemployment coupled with labor-force growth might show employers are becoming more robust in their hiring abilities, Court said. In turn, that might lead to more out-of-work people returning to the job hunt.

“As unemployment drops,” Court said, “people are becoming less discouraged and are jumping back into the labor force.”

In October, around 102,210 people living in Whatcom County had jobs.

The private sector added 600 jobs last month. Since October 2011, private employers have grown their worker base by 2,400.

Court said all private industries have shown year-over-year growth.

Whatcom’s leisure and hospitality sector shed 300 jobs last month, but Court said those losses were fairly typical for the time of year.

The county added 1,600 jobs in the public sector last month, bucking the recent trend of government losses.

The uptick was likely due to increases in part-time and temporary workers in a variety of arenas, including school districts and public works departments, Court said.

Whatcom had one of the lowest unemployment rates last month among counties in northwestern Washington.

Skagit County posted a 8.1 percent unemployment estimate. Snohomish County was at 7.1 percent, and Island County was at 7.3 percent.

San Juan County has the lowest estimate in the entire state at 5.1 percent last month.

Wahkiakum, a tiny county located in the state’s southwest corner, had the highest rate at 11.7 percent.

Last week, state economists pegged statewide unemployment during October at 8.2 percent. The national rate was estimated at 7.9 percent.

The state and national rates are seasonally adjusted, but preliminary estimates on the county level are not due to their small sample sizes.

Contact Evan Marczynski at emarczynski@bbjtoday.com or call 360-647-8805.