American Legion riders Bill Young, James Petito and Bill Polk sport red, white and blue goatees as they prepare for the 2018 Ride of the Patriots during Rolling Thunder in Fairfax, Va. Photo by Cheryl Diaz Meyer / The American Legion

American Legion Post 177 service officer Brad Watkins lays out the ground rules and offers tips to Legion members participating in 2018 Rolling Thunder Ride of the Patriots. Photo by Cheryl Diaz Meyer / The American Legion

American Legion Rider Ben Taylor salutes the flag as the National Anthem is played as Riders gather at Post 177 in Fairfax, Va., for the 2018 Rolling Thunder Ride of the Patriots. Photo by Cheryl Diaz Meyer / The American Legion

Dede Bratton, wife of Army veteran Michael Bratton, wept during a rendition of Amazing Grace as Legion Riders gathered at American Legion Post 177 in Fairfax, Va. before the 2018 Rolling Thunder Ride of the Patriots. Michael Bratton served in Iraq, Afghanistan and Somalia. Photo by Cheryl Diaz Meyer / The American Legion

An American Legion Rider places a memorial to Allen Fary on the back of a motorcycle as Legion members and other veterans gather in the Pentagon parking lots to await the start of the 2018 Rolling Thunder Ride of the Patriots . Photo by Cheryl Diaz Meyer / The American Legion

American Legion Riders joined an estimated crowd of around 500,000 veterans and supporters in the 2018 Rolling Thunder Ride of the Patriots. Photo by Cheryl Diaz Meyer / The American Legion

American Legion Rider Jim Twet of Lorton, Va. watches fellow bikers depart for the 2018 Rolling Thunder Ride of the Patriots. Photo by Cheryl Diaz Meyer / The American Legion

Patriotic crowds cheer from the overpasses as American Legion Riders make their way from Post 177 in Fairfax, Va., to the Pentagon parking lots to await the start of the 2018 Rolling Thunder Ride of the Patriots. Photo by Cheryl Diaz Meyer / The American Legion

Nam Nguyen, a former South Vietnamese soldier and prisoner of war, right, offers cookies to a Vietnam veteran waiting in the Pentagon parking lots for the start of the 2018 Rolling Thunder Ride of the Patriots. Nguyen and his family have been attending the event for 17 years offering veterans sweets, fruit and water. "These guys fought alongside us," said Nguyen. "They are my brothers. 58,000 American soldiers died in Vietnam, and we will never forget them." Photo by Cheryl Diaz Meyer / The American Legion

American Legion Riders joined an estimated crowd of around 500,000 veterans and supporters in the 2018 Rolling Thunder Ride of the Patriots. Photo by Cheryl Diaz Meyer / The American Legion

School children cheer American Legion riders and other veterans as they ride down Constitution Avenue in the 2018 Rolling Thunder Ride of the Patriots. Photo by Cheryl Diaz Meyer / The American Legion

Huge crowds cheer American Legion riders and other veterans as they ride down Constitution Avenue in the 2018 Rolling Thunder Ride of the Patriots. Photo by Cheryl Diaz Meyer / The American Legion

American Legion Riders ride past the U.S. Capitol during the 2018 Rolling Thunder Ride of the Patriots. Photo by Cheryl Diaz Meyer / The American Legion