Before you start drinking for Memorial Day, take a moment to learn the history behind the observance. It’s more than just a long weekend full of barbecue — it's a patriotic holiday intended to honor the Americans who have protected the country.

Memorial Day was started as a way to remember the more than 620,000 people who died in Civil War, which has been called the bloodiest conflict on U.S. soil. The first official Memorial Day observance took place in 1866 in Carbondale, Illinois, but the official “birthplace of Memorial Day” is Waterloo, New York, according to CNN. At the time, it was referred to as Decoration Day.

Over the years, the observance widened in scope to include all American casualties of war. It became a formal national holiday in 1971 and has been observed ever since.

“The Americans who rest beneath these beautiful hills, and in sacred ground across our country and around the world, they are why our nation endures,” President Barack Obama said in a speech commemorating Memorial Day last year. “Each simple stone marker, arranged in perfect military precision, signifies the cost of our blessings. It is a debt we can never fully repay, but it is a debt we will never stop trying to fully repay. By remaining a nation worthy of their sacrifice.”

Learn more about Memorial Day below with facts compiled from the Huffington Post, USA Today, the FW and the Department of Veterans Affairs:

Cities like New York hold parades on Memorial Day while places like Washington, D.C., hold concerts.

Under an act signed by then-President Bill Clinton in 2000, Americans are supposed to pause and remember the deceased at 3 p.m. on Memorial Day.

More than 100,000 more Union soldiers died in the Civil War than Confederate soldiers. 

Fewer than 5,000 people died in the Revolutionary War.

Some people wear red poppies on Memorial Day to honor soldiers who have died.

Another tradition is to place coins on the graves of soldiers you visit. Different coins mean different things: Pennies mean you stopped by, dimes mean you served with the deceased and quarters mean you saw his or her death.

The “Taps” call is often played at military funerals. 

More than 2 million people are expected to go through airport security lines this weekend alone.

The Indianapolis 500 auto race is always held over Memorial Day weekend. This year is the 100th annual event. 

Memorial Day is considered the start of summer in the U.S. because it's followed by warm weather.

About 5,000 people will attend a ceremony at Arlington Cemetery this weekend. It’s 624 acres and in Arlington, Virginia, across the Potomac River from Washington.

About 30 people are buried at Arlington Cemetery every weekday.

Some states also celebrate Confederate Memorial Day, during which they honor fallen Confederate soldiers. The states include Virginia, Texas and Alabama.