Although officially, World War I ended on 28 June 1919, a cessation of the fighting between the Allied forces and Germany went into effect on the eleventh hour of the eleventh day of the eleventh month some seven months earlier. 

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Joseph Ambrose, an 86-year-old World War I veteran, attends the dedication day parade for the Vietnam Veterans Memorial in 1982. He is holding the flag that covered the casket of his son, who was killed in the Korean War
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Originally called Armistice Day, the “holiday” was to be a celebration marked by parades and public meetings and a work stoppage until 11 A.M. Initially the day was set aside to honor veterans of World War I, but in 1954 the 83rd Congress, amended the Act of 1938 to honor all veterans. By 1954, American soldiers had also known service in World War II and the Korean War. Public Law 380 went into effect on 1 June 1954; it made November 11 the day to celebrate the sacrifice of all American veterans of war.

Of the “holiday,” President Woodrow Wilson said, “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 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…”

From the U. S. Department of Veterans’ Affairs we learn, “An Act [53 Stat. 351; U. S. Code, Sec. 87a] approved May 13, 1938, made the 11th of November in each year a legal holiday – a day to be dedicated to the cause of world peace and to thereafter celebrated and known as “Armistice Day.” Armistice Day.”

On October 8, 1954, President Dwight D. Eisenhower issued the first Veterans’ Day Proclamation. [View a copy of the National Register from Tuesday, October 12, 1954 for the First Veterans Day Proclamation in its entirety.] Eisenhower said, “In order to insure proper and widespread observance of this anniversary, all veterans, all veterans’ organizations, and the entire citizenry will wish to join hands in the common purpose.” Every VA administrator since 1958 has served as Chairman of the Veterans Day National Committee.

Unknown U.S. soldier from the North African American Cemetery http://www.history.army.
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On June 28, 1968, the Uniform Holiday Bill created three-day weekends to stimulate industrial and commercial ventures. Federal employees were to mark George Washington’s birthday, Memorial Day, Veterans Day, and Columbus Day. The first of these 3-day weekends to celebrate veterans Day came on 25 October 1971. Needless to say this did not set well with veterans’ groups, which thought the change of days took away from the significance of the celebration. Therefore, President Gerald Ford (on 20 September 1975) signed Public Law 94-97, which changed the annual observance of Veterans Day to its original November 11 date, no matter upon what day of the week the eleventh of November comes. 

For more information on Veterans Day, check out these sources: 

The U. S. Department of Veterans Affairs 

History.com

Military.com

U. S. Army Center of Military History