TABLE 2 Driver and Front Seat Passenger Seat Belt Use: Before and After Enactment of the Primary Occupant Restraint Law on the San Carlos Apache Reservation, 2011 to 2013

Enforcement Phase (Time Period)	N	No. Wearing Seat Belt	Percent Seat Belt Use	(95% CI)
Pre-enactment of primary seat belt law (Jan to Dec 2011)	445	86	19.3%	(15.7, 23.0)
Enforcement grace period^a (Feb to Apr 2012)	237	72	30.4%	(24.5, 36.2)
Full enforcement of primary seat belt law (May to Dec 2012)	822	354	43.1%	(39.7, 46.5)
Full enforcement of primary seat belt law (Jan to Dec 2013)	851	400	47.0%	(43.7, 50.4)

↵a Police officers stopped vehicles if occupants were not restrained but only issued warning citations.