It’s Memorial Day: We Remember All the Fallen!

Memorial Day is a U.S. holiday that is officially about mourning the nation’s fallen service members, but it has come to signal the unofficial start of summer and a long weekend of travel and discounts on anything from mattresses to lawn mowers.

Here is a look at the holiday and how it has evolved:

When is Memorial Day?

It falls on the last Monday of May. This year, it is May 25.

Why is Memorial Day celebrated?

It’s a day of reflection and remembrance of those who died while serving in the U.S. military, according to the Congressional Research Service.

The holiday is observed in part by the National Moment of Remembrance, which encourages all Americans to pause at 3 p.m. for a moment of silence.

What are the origins of Memorial Day?

The holiday’s origins can be traced to the American Civil War, which killed more than 600,000 service members, Union and Confederate, between 1861 and 1865.

The first national observance of what was then called Decoration Day occurred May 30, 1868, after an organization of Union veterans called for decorating war graves with flowers that were in bloom.

The practice was already widespread. Waterloo, New York, began a formal observance on May 5, 1866, and was later proclaimed to be the holiday’s birthplace.

Yet Boalsburg, Pennsylvania, traced its first observance to October 1864, according to the Library of Congress. And women in some Confederate states decorated graves before the war’s end.

David Blight, a Yale history professor, points to May 1, 1865, when as many as 10,000 people, many of them Black, held a parade, heard speeches and dedicated the graves of Union dead in Charleston, South Carolina.

A total of 267 Union troops had died at a Confederate prison and were buried in a mass grave. After the war, members of Black churches buried them in individual graves.

“What happened in Charleston does have the right to claim to be first, if that matters,” Blight told The Associated Press in 2011.