Unemployment in Butler County is at its lowest level since 2008.

In December, the unemployment rate in the county was 4.2 percent. January 2008 was the last time unemployment hit 4.2 percent.

Rick Tannery, a business professor at Slippery Rock University, said the reason for this low number likely is a combination of two factors. One is more jobs.

“In many cases, the economy has improved and there’s more hiring,” Tannery said.

He said some of these jobs may be part-time, but he said that still means companies are hiring.

The other factor is that the labor force has gotten smaller.

“So, people might have dropped out,” Tannery said.

He said the age of workers could be a factor, with more people retiring now and making the labor force smaller.

He said he thinks the southern part of the county likely is doing better than the northern part because of its proximity to a large number of jobs in Pittsburgh.

“I think it’s doing pretty well,” Tannery said.

He said the financial crisis in 2008, and the uncertainty that it brought, was the cause for unemployment rising over the past several years.

“There was a lot of fear out there,” Tannery said, saying there was no construction spending and banks were not giving out many loans.

It took a while for the economy to get better. It started improving around 2013, he said.