The United States observes Memorial Day Monday.
Many Americans have the day off from work and school. The three-day weekend is seen as the unofficial start of the summer vacation season. Many families have picnics or make trips to beaches, parks or campgrounds.
Officially, Memorial Day, observed on the last Monday in May, has been set aside to honor all who died during military service throughout U.S. history. Congress declared Memorial Day a national federal holiday in 1971.
Observances around the country and in Washington are planned for the day. President Donald Trump will participate in a wreath-laying ceremony at the Tomb of the Unknown Soldier at Arlington National Cemetery.
Ahead of the ceremony, Trump said "those who died for our great country would be very happy and proud at how well our country is doing today."
Memorial Day began in 1865, just after the end of the Civil War, when a group of former slaves held what is seen as the first commemoration of the nation's war dead.
The group exhumed the bodies of more that 250 Union soldiers from a mass grave at a Confederate prison camp in Charleston, South Carolina, and gave them a proper burial.
For more than 50 years, the holiday only remembered those killed in the Civil War, not in any other American conflict.
It was not until America's entry into World War One that the tradition was expanded to include those killed in all wars.
On Sunday, the event known as Rolling Thunder, involving thousands of war veterans and others on motorcycles, rolled into Washington as they do every year, passing the monuments on the National Mall, to honor U.S. soldiers missing in action in foreign wars. Their motorcycles can be heard from kilometers away, long before they are seen.
According to the website of Rolling Thunder's Washington chapter the ride is "an actual demonstration/protest to bring awareness and accountability" to the prisoners of war and soldiers missing in action who have been left behind.
Rolling Thunder's motto is: "We will not forget."
In Photos: Memorial Day
