Wreaths at the Freedom Wall at the National World War II Memorial in Washington. (Marvin Joseph/The Washington Post)

(Note: I’ve published some of this before, but here, again, is a brief history of Veterans Day, with some updated information from the Census Bureau on our nation’s veterans.)

The 11th hour of the 11th day of the 11th month.

That’s when the armistice ending World War I began in 1918, and that is the origin of Veterans Day (note that it is spelled without an apostrophe), a U.S. holiday often confused with Memorial Day.

Memorial Day honors America’s war dead, while Veterans Day honors all American veterans, living and dead, and has a special emphasis on thanking living veterans for their service to the country.

In November 1919, one year after the armistice ending World War I went into effect, President Woodrow Wilson declared Nov. 11 as the first commemoration of Armistice Day with the following words:

To us in America, the reflections of Armistice Day will be filled with solemn pride in the heroism of those who died in the country’s service and with gratitude for the victory, both because of the thing from which it has freed us and because of the opportunity it has given America to show her sympathy with peace and justice in the councils of the nations. . . .

In 1938, Congress made Nov. 11 an annual, legal holiday known as Armistice Day to honor the cause of world peace, but it was primarily used to honor World War I veterans. After World War II, in 1954, the law was changed, and “Armistice” was changed to “Veterans.” Nov. 11 became a day to honor veterans of all American wars.

Veterans Day was moved to the fourth Monday in October in 1968 by Congress, but that was reversed in 1978 when it became obvious that Americans wanted the holiday celebrated Nov. 11.

Other facts about the holiday:

The Tomb of the Unknowns: In 1921, the United States laid to rest the remains of a World War I American soldier — his name “known but to God” — in Arlington National Cemetery in Virginia on a hillside overlooking Washington. It became known as the “Tomb of the Unknown Soldier” and was meant to symbolize reverence for the American veteran. Today it is known as the “Tomb of the Unknowns.”

At 11 a.m. on Nov. 11, a color guard consisting of  members of every branch of the military renders honors to America’s war dead at the Tomb of the Unknowns. The president or a representative places a wreath at the tomb, and a bugler sounds taps.

And here are some key economic and demographic statistics compiled by the Census Bureau on our nation’s veterans.

18.5 million — The number of military veterans in the United States in 2016.

9.2 million — The number of veterans ages 65 and older in 2016. At the other end of the age spectrum, 1.6 million were younger than 35.

6.7 million — The number of Vietnam-era veterans in 2016. Moreover, there were 7.1 million who served during the Gulf War (representing service from August 1990 to present); 768,263 who served in World War II; 1.6 million who served in the Korean War; and 2.4 million who served in peacetime only.

14.4 million — The number of veterans who voted in the 2016 presidential election. In that election, 69.6 percent of veterans cast a ballot, compared with 60.6 percent of nonveterans. These rates reflect the citizen voting-age population.

398,453 — The number of all U.S. employer firms that are majority owned by veterans. Veteran-owned firms make up 7.2 percent of the nation’s 5.5 million employer businesses.