NPR data journalist Matt Stiles recently posted this informative infographic of the most common birth dates in the United States. It was constructed using data compiled by Harvery Kennedy School professor of public policy Amitabh Chandra, and later published in the New York Times. Chandra's table relies exclusively on birth date figures from 1973 to 1999.
The most popular birth date is September 16 (I was born on September 13). The least popular date is split between February 29 and December 25.