Silent sentries in more than 500 cities and towns in 25 states keep watch over intersections, snapping photos and shooting video of drivers who run red lights. The cameras are on the job in metropolitan cities like Houston and Chicago and in small towns like Selmer, TN, population 4,700. The red light cameras in Los Angeles will have to come down in a few weeks. That puts the nation’s second-largest city at the leading edge of an anti-camera movement that appears to have been gaining traction across the country in recent weeks.