When it’s your favorite person’s special day, there are usually a few things you have to happen. A cake, balloons, presents, and the singing of “Happy Birthday.” But did you know that you don’t just ...

“Happy Birthday” may be the Hill sisters' main claim to fame, but Patty (left) and Mildred's (right) impact on American history extends far beyond the beloved song. Illustration by Meilan Solly / ...