Decades ago, an interstate agreement was created that allowed states to communicate with each other concerning certain criminal offenses – so that an offense committed by a driver in one state would be reported to the state in which that driver's license had been issued. On Ask the Lawyer, Brendan Bukalski discusses this in more detail: http://www.theintelligencer.com/commentary/article/Consequences-of-out-of-state-traffic-tickets-12150328.php