Galen Rupp became the first American man to win the Chicago Marathon since 2002 and three-time Olympic gold medallist Tirunesh Dibaba stormed to an emphatic victory in the women's race on Sunday.
Rupp, a bronze medallist over this distance at Rio 2016, marked the 40th anniversary of the event with a long-awaited home success in the men's race.
The 31-year-old from Portland, running in only his fourth marathon, clocked two hours, nine minutes and 20 seconds to take the victory after finishing second in the Boston Marathon six months ago.
Rupp made his move in the 24th mile and there was no catching him as America's wait for a first male winner of the race since Khalid Khannouchi finally ended.
Defending champion Abel Kirui crossed the line 28 seconds behind in second place, with fellow Kenyan Bernard Kipyego taking third spot.
Rupp said: "It's just incredible. You train so hard year in and year out, day in and day out and to have a race like this where it all comes together and be able to win in a city that really is such a special place to me, given that my dad grew up here - words can't express the feeling of crossing the line."
Dibaba was in a class of her own in the women's race, winning in a time of 2:18:31.
The Ethiopian had set her sights on the course record of 2:17:18 and although that proved to be beyond her, Dibaba eased to victory almost two minutes ahead of Brigid Kosgei of Kenya, while home favourite Jordan Hasay was third.
Dibaba hit the front before the halfway mark and although Kosgei stuck with her for around six miles, the treble Olympic champion opened up a significant lead at the 19-mile stage and there was only going to be one winner.
"This is my third marathon and I'm very happy to have won here," Dibaba said. "I worked very hard for this."