On the side of a busy expressway in northern Puerto Rico, dozens of cars stand in a line, parked at careless angles off the shoulder. Drivers hold their phones out of car windows; couples walk along the grass raising their arm skyward.
This is not a picturesque stretch of road. It's about 90 degrees out, and the sun is beating down relentlessly. All you can hear is the rumble of cars and trucks passing by, sometimes dangerously close. Then, inside a Ford Escape near the edge of the highway, Casandra Caba exclaims, "Look!"