BOSTON — The cheers were louder, the runners more determined, the tears of joy and relief at the Boston Marathon finish line Monday more heartfelt than ever.

And yes, the security was tighter.

But on a brilliant spring day, the city brought to grief by terrorist bombings one year earlier sprinted back in the resolute style of the runners who tore through quiet suburbs and charming town squares to the finish line, where the roars grew deafening as Meb Keflezighi became the first American man to win the marathon since 1983.

"It couldn't happen at a better time, to win for the United States," said Keflezighi, who charged down Boylston Street with competitors close behind. He held his hands out in victory while crossing the finish line at 2:08:37. The UCLA graduate and naturalized U.S. citizen emigrated from Eritrea in 1987. About 10 minutes later, Kenya's Rita Jeptoo became the first woman to cross the line, setting a course record at 2:18:57.

Cheering masses packed in along the metal barriers surrounding the finish, many wearing blue-and-yellow "Boston Strong" T-shirts. They waved flags, rang cowbells and screamed support for the runners.

Patrick Downes and Jessica Kensky, each of whom lost a leg in last year's bombings, competed as hand-cyclists. Married now, they held hands as they rolled across the finish line.

The fact that this spot had been the scene of carnage a year earlier did not deter the runners, or the spectators. Runners included Phil Kent, Jennifer Hartman and Renee Opell, all from Los Angeles, who were half a block from the finish line last year when the bombs went off. This time, the friends crossed together.

One of those cheering them on was Mark Donnellan. He stood on the same spot, near the Forum Restaurant, where he had been last year when his son, also named Mark, finished the race. They missed the bombs that killed three spectators and wounded more than 260 others by about a minute. But they knew they had to return this year, even as spectators.

"It's irrational to be afraid," said the younger Mark, 27, as the national anthem played and officials handed each of the first finishers a trophy, a wreath and a medal.

"It makes me feel patriotic" to be here, his father said.

Many racers hoped to finish by 2:49 p.m., the exact time two pressure-cooker bombs went off last year, 12 seconds apart.

Those who made it joined a short but poignant tribute to the dead and the wounded, briefly falling quiet and taking off their hats in remembrance. Then, an announcer with a microphone urged them to make some noise, "to signify how this city has come forward."

"Take it forward with a yell that they will hear," he bellowed.

The crowd complied.

The race began 26.2 miles away, in the town of Hopkinton, with the national anthem and a moment of silence for the bombing victims: Martin Richard, Krystle Campbell and Lu Lingzi, along with MIT Police Officer Sean Collier, who officials say was shot to death by the bombers after the attack.

"Today's gonna be special," Boston Police Commissioner William Evans said.

And it was.

Mobility-impaired racers got the first of several staggered start times. Running on prostheses or with other physical limitations, they bounded along roads lined with lawn chairs and people who had been out since 7 a.m. to get the best viewing spots.

"It has always carried such importance, but it's more of an emotional tug this year," said Denise O'Brien, who grew up in the area and watches the marathon every year.

Then came the wheelchair racers and the hand-cyclists, streaking past the growing crowds as they used their powerful arms to propel themselves along the hilly route.

The elite women started at 9:32 a.m., the elite men at 10 a.m. By then, the streets were jammed with spectators and thousands of volunteers filling paper cups with water and Gatorade for thirsty marathoners.

People climbed lampposts to get better vantage points, held out their hands to give high-fives to passing runners, and greeted the police, National Guard troops and other security forces on patrol.

Signs, many of them posted the evening before, dotted trees and lampposts along the way.

Some were inspiring. "Run, Mom, run!" "Anne, don't give up!"

Others were designed to make weary runners smile. "Chafe now, brag forever." "Run like you stole something."

With the elite runners underway, it was time for the rest of the pack, nearly 30,000 strong, to hit the road.

Michelle Jacobsen didn't expect to get emotional, but she began to cry as she jostled her way to the start point, passed beneath a sign reading "Good luck runners," and started to run. "Just that the city comes together for this," she said at the finish line, explaining the flood of feelings that came over her from her first steps.

By mile 23, she was tempted to walk, but she kept running. "I kind of kicked it forward," the Newport Beach woman said.

After finishing, Jacobsen stood at the bomb site, taking in the crowd. She had hoped to stand here last year after running her first Boston Marathon. Instead, she went to shower and never made it back because of the blasts.

This year, Jacobsen was determined to enjoy the moment as long as possible. She planned to head to the airport, still in her running clothes, later Monday and hop on a plane to get back to L.A. in time for work Tuesday.

Mike Poitras was also at the finish line, with his two sons. His shaved head was painted blue and yellow, with the words "Boston Strong" on one side. He wore a Boston Strong T-shirt and carried a sign that read: "No More Hurting People. Peace."

The inspiration for his sign came from bombing victim Martin Richard, 8, who made a similar sign after the 2012 Trayvon Martin killing.

"We always go to the finish line," Poitras said, "but this year, more than ever."

tina.susman@latimes.com

alana.semuels@latimes.com

Times staff writers Nathan Fenno and Stacey Leasca contributed to this report.