Flags are at half-staff in New Hampshire today. Here’s why

President Trump has ordered flags to be flown at half-staff across the United States in honor of National Pearl Harbor Remembrance Day.

Celebrated on Dec. 7 each year, National Pearl Harbor Remembrance Day remembers the 1941 attack at the United States Naval Base at Pearl Harbor in Hawaii, which began the United States’ involvement in World War II. The surprise attack from the Japanese military resulted in the deaths of thousands of service members and civilians, as well as over a thousand injuries.

In memory of the lives lost during the attack on Pearl Harbor, the flag of the United States at all public buildings and grounds across the country and its territories – including in New Hampshire – will fly at half-staff from sunrise to sunset on Sunday, Dec. 7.

Why are flags flown at half-staff?

According to the official website of the U.S. General Services Administration, flags typically fly at half-staff when the country or specific state is in mourning. Observances include national tragedies, days of remembrance and deaths of government or military personnel.

The president, the state governor or the mayor of Washington, D.C., can order flags to fly at half-staff.

What is Pearl Harbor Remembrance Day? What to know about 1941 attack that sent US into WWII

Half-staff vs. half-mast

While half-staff refers to lowered flags on land, half-mast refers to those at sea. Both refer to a flag being flown beneath the top of its staff as a sign of respect.

Emily DeLetter of the USA TODAY Network contributed to this report.