(180527) -- WASHINGTON, May 27, 2018 (Xinhua) -- People participate in the annual Rolling Thunder motorcycle ride to commemorate Memorial Day in Washington D.C., capital of the United States, on May 27, 2018. Hundreds of thousands of motorcycle riders descended on the nation's capital on Sunday for the 31st annual Rolling Thunder Ride for Freedom to honor Memorial Day. (Xinhua/Yang Chenglin)