Most people are surprised to know that National Doughnut Day — traditionally celebrated on the first Friday of June — has a legacy that is almost 80 years old.

It was established in 1938 by the Chicago unit of the Salvation Army to honor women who served doughnuts to soldiers during World War I.  So when you’re enjoying your free donut tomorrow, June 2, think of both the soldiers and the women who also served.

Oh, did we say “free” donut? That’s right, National Doughnut Day is also free donut day across America. Here’s how to get yours:

Participating Dunkin’ Donuts will give you a free classic doughnut of your choice with the purchase of any beverage all day Friday while supplies last. Here’s where to find a Dunkin’ Donuts near you.

If Krispy Kreme is more to your tastes, get one free doughnut of your choice, no purchase necessary at participating locations, found here.

If you pass by a participating Cumberland Farms location between 5 to 10 a.m., you can get a free doughnut with purchase of any dispensed beverage, which includes hot or iced coffee, fountain or frozen drink. Sorry, but this deal is only valid at Cumberland Farms remodeled and “new concept” stores, which you can find by searching here.

Duck Donuts is giving customers a free, made-to-order doughnut of their choice with any purchase. Receipts printed on Friday also will feature a coupon for six free doughnuts when you purchase six. Duck Donut locations are listed here.

If you’ve read this far, we should point out that according to the U.S. Department of Agriculture, a glazed doughnut contains about 240 calories and 120 of those calories are from fat. A medium-size frosted cake doughnut has 251 calories. Of course, none of the shops participating in the National Doughnut Day offers required that customers drive to the location. A nice walk to the store could offset some of those calories.