Easy-to-miss automated speed cameras on its half-mile main drag, where the speed limit is 30 mph, caught 3,500 speeders on their first day of operation last fall. Before that, the norm was six tickets a day.

Many speeders first learn they've been caught when citations, along with photographic evidence, show up at the addresses that match the violators' license plates.

Be forewarned: More than 300 U.S. communities use automated "cop cam" systems like Chevy Chase's. They're after not just speeders but also red-light violators and railroad-crossing jumpers.

In the works are bus-mounted cop cams that ticket bus lane intruders, cop cams to punish speeders in highway construction zones, even cop cam systems that ticket motorists based on a car's average speed over a mile. They catch drivers who brake for known camera sites, then resume speeding