(Photo courtesy: Mothers Against Drunk Driving) (Photo courtesy: Mothers Against Drunk Driving)

Mothers Against Drunk Driving on Monday touted new data that shows that almost 305,000 ignition interlock devices have been mandated nationwide for drivers convicted of drunk driving.

MADD says that states where they are in use have seen declines in the number of drunk driving fatalities. The devices require a driver to blow into the interlock before a car can be started and, in some cases, later during a trip.

According to data collected by Impact DWI, Inc., from companies that supply interlocks, 10,925 are in use in Maryland and 8,456 are being used in Virginia. There was no information collected for the District. Texas (39,027), California (28,129) and Arizona (21,468) were listed as the three leading states for interlock use. It’s estimated there are around about 1 million drunk driving convictions each year.