GDL then and now.

The first comprehensive Graduated License (GDL) law was implemented in Florida in 1996. Now, most states have implemented one or more GDL provision including: extending the time for which a learners permit must be held prior to licensure; passenger restriction; and night driving restriction. Evidence to support each of these provisions existed prior to 1996 and has been largely confirmed with the evaluation of each new state to implement GDL. Nationally, fatal crash involvements of 16 year-old drivers have decreased 23% (1993-1995 vs. 2003-2005). Greater reductions have been seen for crash involvements at night and with passengers. The single most effective GDL provision appears to be the extension of the learners period when this extension has the effect of delaying the time at which unsupervised driving is permitted.