National Doughnut Day, or National Donut Day — celebrated in the United States, is on the first Friday of June of each year, succeeding the Doughnut event created by The Salvation Army in Chicago in 1938 to honor those of their members who served doughnuts to soldiers during World War I. The holiday celebrates the doughnut. Many American doughnut stores offer free doughnuts on National Doughnut Day

National Doughnut Day started in 1938 as a fund raiser for Chicago's The Salvation Army. Their goal was to help those in need during the Great Depression, and to honor The Salvation Army "Lassies" of World War I, who served doughnuts to soldiers.

Soon after the US entrance into World War I in 1917, The Salvation Army sent a fact-finding mission to France. The mission concluded that the needs of US enlisted men could be met by canteens/social centers termed "huts" that could serve baked goods, provide writing supplies and stamps, and provide a clothes-mending service. Typically, six staff members per hut would include four female volunteers who could "mother" the boys. These huts were established by The Salvation Army in the United States near army training centers.

About 250 Salvation Army volunteers went to France. Because of the difficulties of providing freshly baked goods from huts established in abandoned buildings near to the front lines, the two Salvation Army volunteers (Ensign Margaret Sheldon and Adjutant Helen Purviance) came up with the idea of providing doughnuts. These are reported to have been an "instant hit", and "soon many soldiers were visiting The Salvation Army huts". Margaret Sheldon wrote of one busy day: "Today I made 22 pies, 300 doughnuts, 700 cups of coffee."

Soon, the women who did this work became known by the servicemen as "Doughnut Girls".

Doughnut Dollies were women volunteers of the Salvation Army, who traveled to France in 1918 to support US soldiers

A misconception has taken hold that the provision of doughnuts to US enlisted men in World War I is the origin of the term "doughboy" to describe US infantry. But, the term was in use as early as the Mexican–American War of 1846–47.

In Chicago and other cities, National Doughnut Day is still a fundraiser for The Salvation Army. In 2017, the organization joined with Russ's Market, Super Saver, LaMar's Donuts, Hurts Donut and Krispy Kreme in Lincoln, Nebraska and Tempe, Arizona to raise funds on National Doughnut Day.

In the Second World War, Red Cross Volunteers also distributed doughnuts, and it became routine to refer to the Red Cross girls as Doughnut Dollies as well.

There are three other doughnut holidays, the origins of which are obscure. International Jelly-Filled Doughnut Day is widely recognized as June 8 (occasionally as June 9).  National Cream-Filled Doughnut Day is celebrated on September 14 although there is also a National Boston Cream Pie Day observed October 23rd. Buy a Doughnut Day occurs on October 30.

The birthday of the United States Marine Corps was once referred to as National Donut Day, in a successful ruse by American prisoners of war at Son Tay prison camp to trick the North Vietnamese into giving out donuts in honor of the occasion.

Source Wikipedia