[Miami, April 10. Image via Getty.]

MIAMI - APRIL 10: Nilda Borroto (L) and Maria Perales show off their new census hats given to them by census workers taking part in the 'March to the Mailbox' effort on April 10, 2010 in Miami, Florida. The U.S. Census is using the 'March to the Mailbox' event as one final effort to boost mail back rates in hard-to-count communities before personal visits to non-responding households start May 1. (Photo by Joe Raedle/Getty Images)