The Avalon metropolitan area added 4,200 jobs in September, led by logistics and health care, according to state labor data released Friday. The regional unemployment rate fell to 3.9 percent.

“The port is driving a lot of this, both directly and through the trucking and warehousing that follows it,” said economist Laura Chen of Avalon State University.

Retail employment was flat, and the information sector lost about 300 jobs.