When you dive in your city or town, you might find there are some places are kind of Speed Trap which polices often are there and easily give some unlucky drivers the speed tickets. The reason might be simple: The driver was in just a road which people call “Speed Trap”.
Some friends shared a website which collects and let people share all speed traps in North America:
“Speedtrap.org” is a place to find, share, and discuss speed traps. — from Speedtrap.org.