But Phelps is one of the few veterans to have tasted success at the trials as a batch of young, first-time Olympians is stealing the show.
Many fans have come to Omaha to cheer the familiar - Phelps, Ryan Lochte, Missy Franklin all are multiple Olympic medal winners. But as races finish, the fans see relatively unfamiliar names with a "1" next to them. Names like Townley Haas, Kelsi Worrell and Ryan Murphy.
Murphy won the men's 100-meter backstroke in a time of 52:26, a mere 32 hundredths of a second off the world record. Murphy has become one of eight swimmers, so far, to win at the trials and qualify for their first Olympic team.
Murphy, 20, beat two 30-somethings in the final, including 31-year-old Matt Grevers.
"Yeah, I mean both those guys have either kids or kids on the way," Murphy said. "I don't even have a girlfriend! They're definitely a lot more mature than me, but sometimes youth wins out."
"This guy asked me today, 'What do you think about before you swim,' " Phelps said on Tuesday. "I was like, 'Nothing!' " He was like, 'Are you kidding?' " I said, 'No - I don't think about anything.' "
Phelps raced to victory in the 200-meter butterfly, and booked a place for himself in the Olympic team for a fifth time. Phelps has repeatedly maintained that Rio will be his final games. It is to be noted that American Olympians have won more swimming medals than any other country.