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Driving at night increases the fatal crash risk per mile of travel for all drivers, and especially for teenage drivers (Hedlund et al., 2003; Tefft et al., 2013; Williams, 2003). A study found that the rate of driver fatalities was 5 times higher among 16- and 17-year-olds from 10 p.m. to 5:59 a.m. compared to driving during the day (Tefft et al., 2013). At night, driving is more difficult, driver drowsiness is more common, and alcohol is more likely to be used. Many intermediate license drivers have limited experience driving at night. For these reasons, a nighttime driving restriction can help reduce risk for intermediate level drivers.

The restricted hours vary widely, from 6 p.m. to 6 a.m. in the most restrictive State, to 1 a.m. to 5 a.m. in the least restrictive (IIHS, 2021b). The most common hours are 11 p.m. or midnight to 5 or 6 a.m. However, a starting time earlier than midnight will prevent more crashes, especially since teenage driver crashes occur more frequently before midnight than after (Foss & Goodwin, 2003; Shults & Williams, 2016; Williams, 2003). An analysis of fatal crash data for drivers 16 and 17 estimated that while these drivers only take about 11% of their trips from 9 p.m. to 5:59 a.m., these trips account for almost one-third (31%) of fatal crash involvement in this age-group (Shults & Williams, 2016).

NHTSA’s 2007 Motor Vehicle Occupant Safety Survey found that 73% of the general public believe teenagers should not be allowed to drive unsupervised after 9 p.m. (Block & Walker, 2008). Another national survey of parents found 90% support a nighttime driving restriction, with 77% saying it should be 10 p.m. or earlier (Williams et al., 2011). These perceptions match observed driving trends, which show that greater reductions in crash rates are associated with nighttime restrictions starting at or before 10 p.m. (Shults & Williams, 2016). There is an almost two-fold increase in the proportion of young driver (16 and 17) involvement in fatal crashes before midnight compared to after midnight. Twenty-three States and the District of Columbia had nighttime restrictions starting at 12 a.m. or later, with almost 93% of nighttime travel by drivers 16 and 17 ending before midnight.


As of November 2021 there were 49 States and the District of Columbia that restricted intermediate license drivers from driving during specified nighttime hours (the exception is Vermont). Many States allowed driving during the restricted hours for work or school-related activities (IIHS, 2021b).


The effectiveness of nighttime driving restrictions in reducing both nighttime driving and nighttime crashes has been demonstrated conclusively (Fell et al., 2011; Hedlund et al., 2003; Hedlund & Compton, 2005; Lin & Fearn, 2003; Lyon et al., 2012; Masten et al., 2013; McCartt et al., 2010). The earlier a nighttime restriction begins, the greater the reduction in crashes. For example, night restrictions that begin at 9 p.m. are associated with an 18% reduction in fatal crashes compared to no restriction. The reduction is only 9% when the night restriction begins at 1 a.m. (McCartt et al., 2010).


Once GDL is in place, a nighttime driving restriction can be implemented or modified at very little cost.

Time to implement:

GDL requirement changes typically require about 6 months to notify the public and implement the changes.