It’s not that pigs haven’t gotten their due in history: A long line of fictional swine come to mind when the animal is mentioned, from onscreen stalwarts (Babe; Miss Piggy) to figments of the literary imagination (Wilbur; the Orwellian variety) to the one who went “wee wee wee” all the way home. But in 1972, sisters Ellen Stanley and Mary Lynne Rave decided that the animal deserved its own day in the mud. They founded National Pig Day, to be held annually on the first of March, “to accord to the pig its rightful, though generally unrecognized, place as one of man’s most intellectual and domesticated animals.”
Adherents to the national holiday find themselves in two distinct camps: those who celebrate by consuming pork products, and those who mark the day by discouraging such consumption. The latter group makes a plea for human sympathy, pointing to ample research signaling the animal’s intelligence. If one is disinclined to decide, a more neutral approach may be taken by simply enjoying porcine portraits produced by some of the 20th century’s greatest photographers.
Liz Ronk, who edited this gallery, is the Photo Editor for LIFE.com. Follow her on Twitter @lizabethronk.