Veterans Day is November 11 and, being a legal holiday, one would expect that there is actual law behind its existence. And yes, that is true, although some of the earliest documents related to Veterans Day (or, more accurately, its antecedent, “Armistice Day”) are of some lesser legal status.
The documentary history of Veterans Day could start in many places. On November 11, 1918, the day that marked the end of World War I, President Woodrow Wilson addressed a joint session of Congress to announce the armistice. Address by the President of the United States, H. Doc. No. 1339, 56 Cong. Rec. 11537 (Nov. 11, 1918). Many histories of Veterans Day, including this one from the Department of Veterans Affairs (VA), indicate that President Woodrow Wilson “proclaimed” Armistice Day on November 11, 1919, the one-year anniversary of the end of the Great War. However, strictly speaking, a presidential proclamation is an official document of varying legal significance, depending on the topic and the president’s constitutional power with regard to it. For that reason, presidential proclamations are published in U.S. Statutes at Large. But, President Wilson’s “proclamation” wasn’t so published in any official government publication. Rather, it was published in the New York Times (it has since been republished at 64 The Papers of Woodrow Wilson 7 (1991), where it is titled, “An Armistice Day Statement”; The New York Times merely introduced it as “The President’s Message,” “Wilson Sees Cause for Pride in War,” N.Y. Times, Nov. 11, 1919, p. 17). Wikipedia also lists Veterans Day as a day established by presidential proclamation, with a reference to the 1919 “proclamation.”
Returning to the VA history above, there is reference to a 1926 concurrent resolution passed by Congress and asking the president
to issue a proclamation calling upon the officials to display the flag of the United States on all Government buildings on November 11 and inviting the people of the United States to observe the day in schools and churches, or other suitable places, with appropriate ceremonies of friendly relations with all other peoples.
The VA history does not provide a citation to this resolution, though it was published in Statutes at Large. Armistice Anniversary, S. Con. Res. 18, 69th Cong., 44 Stat. 1982 (June 4, 1926). In response, President Coolidge issued just such a proclamation, on November 3 of that year, calling for an observance of November 11. It did not create a legal holiday, as the proclamation included language suggesting that schools would be in session. Proclamation (Armistice Day, 1926), 44 Stat. 2630 (Nov. 3, 1926). President Coolidge also gave a public address on Armistice Day. Calvin Coolidge, “Address at the Dedication of the Liberty Memorial at Kansas City, Missouri,” November 11, 1926, Online by Gerhard Peters and John T. Woolley, The American Presidency Project.
Armistice Day finally became a legal holiday in 1938. Act of May 13, 1938, ch. 210, 52 Stat. 351 (1938), now codified at 5 U.S.C. § 6103. Armistice Day was celebrated as such until 1954. By then, America had been through both World War II and the Korean War, and Congress changed the holiday from a celebration of World War I’s armistice to a celebration of all U.S. war veterans, by renaming the holiday “Veterans Day.” Act of June 1, 1954, Pub. L. No. 83-380, 68 Stat. 168 (1954) (PDF). Thus, on October 12, 1954, in the Federal Register, President Eisenhower published a proclamation recognizing Veterans Day. Proclamation (Veterans Day, 1954), 19 Fed. Reg. 6545 (Oct. 12, 1954) (PDF).
So, we now have Veterans Day celebrated on November 11, right? Wrong. Because in 1971, Veterans Day was celebrated on October 25. Why? Because of the Act of June 28, 1968, Pub. L. No. 90-363, 82 Stat. 250 (1968) (PDF), which made certain legal holidays, including Veterans Day, fall on floating Mondays in order to ensure three-day weekends. According to the VA history, the October 25, 1971 celebration of Veterans Day “was observed with much confusion…” This did not go over well, and Congress reversed course, with the Act of Sep. 18, 1975, Pub. L. No. 94-97, 89 Stat. 479 (1975) (PDF), reverting the celebration of Veterans Day to November 11 annually (many states did this before the federal government).