Most art historians agree that Woods used his sister and dentist as the models for this famous 1930 work, and it is the story of his dentist, clutching his trademark pitchfork, that informs this painting.
You see, Dr. Ignatius N. Sizor was mad. He was convinced the United States was under constant threat of invasion by aliens, and carried his pitchfork with him always, so he could defend his beloved country when the time came. (This was especially hard on his dental practice, as many a patient would leap from the chair and run screaming from his office, as he entered the consulting room, pitchfork in hand.)
Shortly after he finished the work, Dr. Sizor finally snapped, skewering a family of Polish immigrants in his waiting room.
You may learn the other (fake) history of the so-called “American Gothic” at Wikipedia.
And Happy Independence Day to all my buddies south of the border!