The Petty Girl became an American institution thanks to advertisements like this one, from the July 17, 1939 Saturday Evening Post. George Brown Petty IV was already well-known by this time (he began his series of "Petty Girls" for Esquire in 1933), but as he more finely honed his skill in pin-up air brush art, he would happen to peak at the exact right time, just as America was about to enter the Second World War. Few G.I.s did not have a Petty or Vargas print during those war years, art work produced specifically as pin-ups. But the earlier advertisements like this one show that the Petty style was already commonplace by the time the war began.
Interestingly, Petty (who used his daughter as the model for much of his art) maintained a hunting and fishing lodge near Hayward, Wisconsin, near where I grew up. While he was mostly interested in hunting, he did do some angling in those musky waters from time to time.
As for his artwork, I'll have to go with what George Lois, the famed art director at Esquire, once said: "I'm going on the record to swear that George Brown Petty IV consistently created better-designed women than God..."
-- Dr. Todd