Galen Rupp celebrates after winning the men's race at the Bank of America Chicago Marathon on October 8, 2017 in Chicago. "I feel that I have come second so many times before and winning feels great", Rupp, still excited from his achievement said after the race. Kenyan Abel Kirui, the 2016 champion, came in second in 2:09:48.
"It's just incredible", the delighted victor told NBC afterwards.
The last American to win the race was Khalid Khannouchi in 2002.
Ethiopia's Tirunesh Dibaba won the women's race in a time of 2:18:30 ahead of Kenya's Brigid Kosgei +1:53 and American Jordan Hasay (+2:28).
Kenya's Dennis Kimetto, world record holder from his 2014 Berlin Marathon triumph in 2:02:57 and the 2013 Chicago champion, led at the halfway mark in 1:05:49 but began limping soon after and by 25km was off the pace for good.More news: OJ Simpson freed from jail after spending nine years behind bars
"I really wanted to wait", Rupp said.
Dibaba, 32, is a two-time 5,000m world champion and three-time 10,000m world champion.
He made his marathon debut at the 2016 Olympic Trials before a surprise bronze medal over 26.2 miles at the Rio Olympics.
Slocum also races in the Garden State.
"I ran without a pacemaker and It was hard to break a record, but I am pleased with the race and the result today".
And Dibaba was second at the London Marathon in April in 2:17:56, becoming the third-fastest woman at the distance in only her second try. This is now the first time Americans have finished top three in both the men's and women's races at the Chicago Marathon since 1985.