Meb Keflezighi became the first US male athlete to win the Boston Marathon in three decades, in a city still recovering from last year's fatal bombing attack.
Keflezighi, born in Eritrea but is now a US citizen, pulled ahead of a pack of elite African runners a little more than halfway into the race and held off a late challenge by Kenya's Wilson Chebet.
He won the world-renowned race in 2 hours, 8 minutes and 37 seconds to chants of "USA! USA!" from onlookers.
Among the women, Kenya's Rita Jeptoo notched her second consecutive win of the race, smashing a 12-year course record with a blistering official time of 2 hours, 18 minutes and 57 seconds.
Fans had packed the course, waving American flags and wearing T-shirts bearing the "Boston Strong" motto the city adopted as a rallying cry after last year's attack. Their screams grew deafening as Keflezighi tore through the final miles.
Keflezighi said he had been extra motivated to win after seeing the attack last year.
"It was not just about me. ... I was going to give everything I could for the people," he said .
Three people, including an 8-year-old boy, were killed and 264 were hurt when, prosecutors say, a pair of ethnic Chechen brothers left homemade bombs at the crowded finish line, tearing through the crowd.
Some 35,755 runners from 96 countries, including New Zealand, competed in the second-largest field in history for the 118th running of the Boston Marathon.
Wellington property manager Andrew Wharton ran in the marathon last year and decided to return to Boston to compete again.
He told Radio New Zealand's Morning Report programme the atmosphere was "absolutely incredible" and there was tremendous support for runners.