Not quite 23 miles into the race and having just re-crossed Martin’s Point Bridge on his way back to Portland’s Back Cove, Spencer McElwain couldn’t resist a peek. He looked over his shoulder, straining in vain to see his closest pursuer.

“I had just dropped my slowest mile and I got kind of nervous,” he said. “That was just insecurity.”

McElwain, a 27-year-old native of Caribou who ran at the University of Maine and now lives in Portland, could be forgiven. After all, he was the fourth runner to assume the lead of Sunday’s 25th edition of the Maine Marathon.

There would be no fifth. McElwain reached the finish line with a 49-second cushion to win in 2 hours, 31 minutes, 36 seconds.

Runner-up Taylor Days-Merrill, 22, of Fairhaven, Massachusetts, led for the first eight miles before dropping to fourth place. Chris Harmon, 27, of Portland and Stefan Sandreuter, 22, of North Yarmouth also led the race at various points until McElwain took over at a water stop in Mile 16.

“I sped up to get water and then a gap kind of formed,” said McElwain, a former UMaine teammate and current training partner of Harmon. “I started feeling good. That’s when I started to get some of the (north-bound) marathoners and half-marathoners cheering me on. I got maybe too excited, because I felt it at the end.”

The women’s winner was Lauren Jackson, 36, of Augusta, New Jersey. A high school teacher and cross country coach, Jackson finished in 3:06:11 to win by more than 5 minutes over Samantha Johnson, 36, of Brookline, Massachusetts, with Hollie Corbett, 37, of South Portland taking third.

“I wasn’t expecting this,” Jackson said with a laurel wreath on her head and a bouquet of roses in her arms. “I made the trip alone. I have two young kids and a 6-hour drive is not ideal for them, so my husband stayed home with them. It’ll be a nice call home, that’s for sure.”

Maine was simply No. 21 on Jackson’s bucket list of running a marathon in all 50 states. Two weeks ago, she checked off West Virginia.

“Those last 6 miles,” she said, “reminded me I was still a little tight.”

Both McElwain and Jackson received $1,000 for first place. Days-Merrill and Johnson took home $500 for second and Harmon and Corbett $250 for third.

Conditions were ideal for running, less so for spectators. Temperatures remained in the low 50s throughout the morning with occasional misty rain.

“There wasn’t too much wind or anything,” said Jonny Wilson, 28, a Falmouth native who now lives in Flagstaff, Arizona, and might have been the only runner wearing dark shades on a decidedly gray morning. “I always wear sunglasses. It just helps me relax more. Even with the mist, it may fog up the sunglasses a little bit, it still keeps the rain out of my eyes.”

Wilson won Sunday’s concurrent Maine Half Marathon in a course-record time of 1:06:38. Louie Luchini of Ellsworth established the previous mark of 1:06:56 in 2009. Over a different route, back in 1994, Jose Rocha of Peabody, Massachusetts, won in 1:06:23.

“The hills in the middle portion in Falmouth cost me a bit,” Wilson said. “I think at about 11 miles, if I could hold to a 5-minute (mile) pace I could have got (the old-course record) but I wasn’t quite able to.”

His main goal, however, was Luchini’s record. To maintain a 5:05 mile pace for so long, Wilson needed help.

“I’ve run these roads my whole life,” he said. “A lot of people knew who I was and were cheering for me and pushed me along. That makes a big difference when you’re running that far, that hard, by yourself.”

Not quite 6 minutes behind Wilson was runner-up Moninda Marube, 37, of Auburn, winner of the 2014 Maine Marathon. Scott McArthur, 26, of Cambridge, Massachusetts, was another half a minute behind in third.

Michelle Lilienthal, who decided only Thursday to use the half marathon as “progression run” in her marathon training, took first place among women in a time of 1:18:30. Sheri Piers of Falmouth and Erica Jesseman of Scarborough ran alongside Lilienthal, of Portland, until the Half Marathon turnaround point on Route 88 in Falmouth.

“They have races coming up,” Lilienthal, 34, said of Piers (New York City next month) and Jesseman (Hartford next weekend). “Their plan was to be reserved. I knew I wanted to push the second half.”

First prize for Lilienthal and Wilson was worth $500. Piers and Jesseman earned $250 and $150 for second and third, each a little more than two minutes behind Lilienthal.

Results.