Happy birthday, Harley Davidson

Motorcycle enthusiasts arrive for Harley Davidson's 110th anniversary celebration in Milwaukee, Wis., Aug. 29, 2013.

More than 100,000 people are expected for the four-day celebration which features concerts, a parade, street parties and other events.

The Harley Davidson museum is reflected in a gas tank during the Harley Davidson 110th anniversary celebration in Milwaukee, Aug. 29, 2013.

Motorcycle enthusiasts begin to arrive for Harley Davidson's 110th anniversary celebration in Milwaukee, Aug. 29, 2013.

A rider looks for a parking spot along the Milwaukee lakefront during the Harley Davidson 110th anniversary celebration, Aug. 29, 2013.

Motorcycle enthusiasts arrive for Harley Davidson's 110th anniversary celebration in Milwaukee, Aug. 29, 2013.

A rider looks for a parking spot along the Milwaukee lakefront during the Harley Davidson 110th anniversary celebration, Aug. 29, 2013.

Riders make their way along Interstate 94 during the Harley Davidson 110th anniversary celebration, Aug. 29, 2013.

Rider Omar Koya of Mexico takes a picture of the Milwaukee Art Museum at sunset during the Harley Davidson 110th anniversary celebration, Aug. 29, 2013.

A rider makes her way past a row of parked bikes during the Harley Davidson 110th anniversary celebration, Aug. 29, 2013.

A rider makes his way along the lakefront as the sun sets during a Harley Davidson 110th anniversary celebration, Aug. 29, 2013.

A rider looks for a parking spot along the Milwaukee lakefront during the Harley Davidson 110th anniversary celebration, Aug. 29, 2013.