PORTLAND — If last year’s turnout is indicative, at least 3,400 competitors are expected to participate Sunday, Sept. 30, in the 2018 Gorham Savings Bank Maine Marathon.

The 27th annual out-and-back marathon, a Maine Track Club event, begins at 7:45 a.m.

The course winds around Back Cove in Portland, up through coastal Falmouth and into Yarmouth. It features “rolling hills and views of the Portland skyline, Casco Bay, and peak fall foliage,” according to the event website.

There is no same-day registration, but online registration remains available through Friday, Sept. 28, at mainemarathon.com.

Race day includes a full marathon, a half marathon and a marathon relay, which is described as “a unique two- to four-person marathon-length event.” Both the marathon and half marathon are USA Track and Field-certified and the marathon is a qualifier for the Boston Marathon.

In addition, about 40 percent of race proceeds go to charity. This year the receiving organizations are Greater Portland Health, the Ronald McDonald House Charities of Maine, and The Locker Project.

Road closures will include Baxter Boulevard, 5 a.m.-2 p.m.; Depot Road in Falmouth, from U.S. Route 1 to Route 88, 8 a.m.-1 p.m; Route 88 in Falmouth north of Depot Road, 8-10:30 a.m; Johnson Road in Falmouth, from U.S. Route 1 to Route 88, 8 a.m.-1 p.m, and Gilman Road in Yarmouth, from Route 88 to Prince’s Point Road, 9-11 a.m.

Spectators are asked not to park on Route 88 at any point on the course. Racers can be tracked through an app called RaceJoy, which shows where they are on the course and allows friends and family members to send virtual cheers.

This story has been updated.