CHRISTMAS COMES but once a year. For a while, however, Thanksgiving came twice, and though there was a Depression on and a world war looming, Americans managed to devote quite a lot of time and energy to an angry dispute over when our day of thanks and unity should be observed. The uproar began in 1939, when President Franklin D. Roosevelt, known as “that man” to his detractors, issued a Thanksgiving Proclamation for Nov. 23 instead of Nov. 30, which, in that year, happened to be the last Thursday of the month, the day set aside for Thanksgiving ever since the Civil War. The president was responding to pleas from many of the country’s merchants, who opposed a late Thanksgiving because it shortened the Christmas shopping season.

The change seemed simple and benign, but it triggered waves of indignation (and some support) as well as intense lobbying, and the letters came rolling in to the White House. From the Downtown Association of Los Angeles: “You will appreciate the importance that an additional week incorporated in this great holiday season will have upon the distribution activities of the entire United States.” From the owner of Arnold’s Men’s Shop in Brooklyn: “The small storekeeper would prefer leaving Thanksgiving Day where it belongs. If the large department stores are over-crowded during the shorter shopping period before Christmas, the overflow will come, naturally, to the neighborhood store. Before writing, [I] have consulted with my fellow directors of the Flatbush Chamber of Commerce.” From a manufacturer of calendars and gift cards: “I am afraid your change for Thanksgiving is going to cause the calendar manufacturers untold grief. If very many customers demand 1940 calendars to correspond with your proclamation, hundreds of thousands of dollars will be lost by the calendar companies, and in many instances it will result in bankruptcy.”

But the president persisted in proclaiming the fourth Thursday of November as Thanksgiving Day. To many, the diktat seemed confirmation of their worst fears about Roosevelt — FDR to U.S.: Shut up and eat your mashed potatoes. The controversy soon took on a heavily partisan character. Polling showed that Democrats favored the new Thanksgiving by a narrow majority, while Republicans were overwhelmingly opposed to what some called “Franksgiving.” There was talk of Republican and Democratic Thanksgivings. The president’s unilateral act was likened by Alf Landon, whom he had defeated in the 1936 election, to those of dictators such as Hitler, though it had no legal effect outside the District of Columbia and the territories of Alaska and Hawaii. Many states chose to observe FDR’s chosen day, but others stuck to tradition. Congress in 1941 passed a joint resolution backing the president’s position, and if there were any 10th Amendment issues, the Supreme Court did not take them up. (Antonin Scalia was only 5 years old at the time.) Still, it was several years before all the states went along.

Today, Thanksgiving is a settled issue, its observance cemented in place by goodwill, consensus and the National Football League’s scheduling department. We have just come through another fractious campaign in which the results were, if not universally approved, generally accepted. There are many factions in America, as always, but only one Thanksgiving, and it is neither Democratic nor Republican — a state of affairs for which all can be thankful, from the Downtown Association of Los Angeles to the Flatbush Chamber of Commerce.