Memorial Day falls on the last Monday of May. Americans all over the country honor fallen service members with parades, barbecues and commemorative services.

Though Memorial Day was made an official federal holiday in 1971, its roots trace all the way back to the Civil War, when Northerners and Southerners alike were looking for a way to publicly mourn their fallen. Most observances were concentrated in the South, where the most Civil War graves were located.

Over 25 cities claim to be the birthplace of Memorial Day. For example, Macon, Georgia, claims it began there in 1866, while Boalsburg, Pennsylvania, maintains it began there in 1864.

One story maintains that, in late April of 1866, a group of Mississippi women went to decorate the graves of soldiers who had died in the Battle of Shiloh. When they arrived, they found the Confederate graves well cared for, in stark contrast to the nearby graves of Union soldiers, which were bare and unkempt. Saddened, the women placed their flowers on the Union graves, too.

On May 5, 1868, just three years after the Civil War, a group of Union veterans known as the Grand Army of the Republic declared May 30th to be Decoration Day. Maj. Gen. John A. Logan gave the order for his posts to decorate graves “with the choicest flowers of springtime.”

“Let no neglect, no ravages of time, testify to the present or to the coming generations that we have forgotten as a people the cost of a free and undivided republic,” he wrote.

The first major organized Decoration Day observation occurred that year on May 30th at Arlington National Cemetery. Ulysses S. Grant presided over the ceremony. After the speeches, children from local orphanages walked through the cemetery with members of the Grand Army of the Republic, placing flowers on the graves of Union and Confederate soldiers.

Today, several states continue to observe Confederate Memorial Day, in which they honor only Southern soldiers who died during the Civil War. These states are North Carolina, South Carolina, Texas, Alabama, Virginia, Louisiana, Mississippi, Tennessee and Georgia. Confederate Memorial Day, also known as Confederate Heroes Day (in Texas) and Confederate Decoration Day (Tennessee), is celebrated in conjunction with the national holiday.

Today, most Southern states, including Florida, Louisiana, North Carolina, Texas, Tennessee and Virginia, no longer include it as an official holiday where government offices close, but there are a few that still do. In South Carolina, for example, eight of its 46 counties gave their government workers paid leave on May 10.

Though it occurs on different days in different states, Confederate Memorial Day is generally celebrated with church services and civil war re-enactments. Flags and flowers are placed on confederate graves, and civil war relics are displayed.

On a national level, Decoration Day was expanded to honor all fallen U.S. service members after the end of WWI. In 1971, it became a federal holiday, with an official National Moment of Remembrance. At 3 p.m. local time, every American is encouraged to pause in silence for a minute to reflect on the sacrifice of the service members who gave their lives for this country.

We encourage you to reflect on those who gave their lives in defense of our country.

This story originally appeared May 26, 2016, on the web site of American History Magazine, a sister publication.