About 7,500 motorcycles sparkled in the sunshine as they growled along the 4.5-mile route by Lake Michigan.
Vannettsa Valentine of Milwaukee watched the parade and slapped hands with many bikers.
"I've lost count of where they all come from," she said. "I wanted to welcome them to Milwaukee."
More than 100,000 people were expected in Milwaukee for the celebration, which included activities at the new Harley-Davidson Museum and a Saturday night performance by Bruce Springsteen and the E Street Band.
Harley-Davidson Inc. spokesman Jerry Gleason said the riders were randomly selected from among people who bought celebration tickets before December.
Riders came from overseas as well as the United States, many festooning their bikes with their home countries' flags. Others wore costumes, including Batman. The 158 police and sheriff's troopers participating included officers from as far away as Italy.
Among the lead riders was Willie G. Davidson, grandson of a Harley-Davidson founder and the company's chief styling officer.
The celebration started Thursday and ends Sunday.