Labor Day weekend traffic on the Maine Turnpike was up 2.1 percent over a year ago, according to the agency that runs the toll highway.

In all, there were just over a million transactions on the 109-mile-long highway over the four days between Friday and Monday. The highway is on pace to have the busiest year on record, said Courtney Erin, spokeswoman for the Maine Turnpike Authority.

With traffic and toll revenue on the rise, the Maine Turnpike Authority expects to have enough cash for a project to expand the highway to six lanes from South Portland to Falmouth by 2027. Joel Page/Staff Photographer

Eight million motorists were counted on the turnpike for the entire month of August.

The strong summer tourism season is extending a year of high volumes of traffic. From January to July, the turnpike experienced a 4.7 percent increase in traffic compared to the same period in 2014.

Nationally, the American Automobile Association estimated that 35.5 million Americans would travel 50 miles or more over Labor Day weekend, which would make it the busiest Labor Day on American roads since 2008.