Did you see, up in the sky? 80 artists sent messages over U.S. detention centers

It is a Fourth of July custom. Fleets of airplanes take to the sky and produce massive typewritten messages in the air. Known as skytyping, these vaporous missives generally serve as advertising for music festivals, summer movies or car insurance and are often generated over public parks and crowded beaches.

Over the holiday weekend, however, some of those messages and their locations were quite out of the ordinary.