According to Krispy Kreme, one of the donut shops giving out a free donut of your choice Friday ....
"National Doughnut Day was established in 1938 by the Chicago Salvation Army to raise funds during the Great Depression and to honor the work of World War I Salvation Army volunteers who prepared doughnuts for thousands of soldiers."
Here's the KK site to find a donut near you
According to this other site ..
"Often, the doughnuts were cooked in oil inside the of the metal helmet of an American soldier. The American infantrymen were commonly called doughboys"
I don't know how true this story is ... but a great Donut Day story about Vietnam
There's even an ecard to commemorate the day
Even if your donut shop isn't offering a freebie ... seems like a good excuse to buy a donut and celebrate the holiday.
If you miss donut day ... here's a year's worth of food holiday ... I'm looking forward to August 21 ... National Spumoni Day