title: Driver licensing and reasons for delaying licensure among young adults ages 18-20, United States, 2012.
abstract: BACKGROUND
  Motor vehicle crashes are the leading cause of death for teens and young adults in the United States. Graduated driver licensing (GDL) systems were designed to protect young novice drivers by limiting their exposure to specific risks while they gain experience driving. In the United States, most states' GDL systems only apply to new drivers younger than 18. Some experts suggest that GDL might encourage young people to wait until age 18 to obtain a license, to avoid GDL requirements, resulting in older teenagers having less driving experience and higher crash risk than they might have had without GDL. This study examined the prevalence and timing of licensure among young adults, and explored factors associated with delaying licensure among those not licensed before age 18.
  
  
  METHODS
  An online questionnaire was completed by 1,039 persons aged 18-20 years, recruited from a representative panel of United States households. Main outcome measures were acquisition of driver's license (a) within 12 months of the state minimum age for licensure, (b) before age 18. Associations of timing of licensure with demographic characteristics were assessed using multivariable logistic regression. Respondents not licensed before age 18 were asked to rate the importance of various possible reasons for delaying licensure.
  
  
  RESULTS
  54% of respondents were licensed before age 18. Blacks (37%; adjusted Prevalence Ratio 0.67, 95% Confidence Interval 0.48-0.93) and Hispanics (29%; adjusted Prevalence Ratio 0.60, 95% Confidence Interval 0.45-0.81) were less likely than non-Hispanic whites (67%) to be licensed before age 18. Lower household income was independently associated with delayed licensure (P < .001). The most common self-reported reasons for not becoming licensed sooner were not having a car, being able to get around without driving, and costs associated with driving.
  
  
  CONCLUSIONS
  There was little evidence that GDL is a major contributor to delayed licensure; however, a substantial minority of young people do not obtain a driver's license until age 18 or older and thus begin driving outside of the GDL system, which in most states only applies to new drivers younger than 18. More research is needed to investigate the safety of older novice drivers.
authors.affiliation: AAA Foundation for Traffic Safety, 607 14th Street NW, Suite 201, Washington, District of Columbia, 20005, USA. btefft@aaafoundation.org.
authors.forename: Brian C
authors.initials: BC
authors.lastname: Tefft
authors.affiliation: Allan F. Williams LLC, 8200 Beech Tree Rd., Bethesda, Maryland, 20817, USA.
authors.forename: Allan F
authors.initials: AF
authors.lastname: Williams
authors.affiliation: AAA Foundation for Traffic Safety, 607 14th Street NW, Suite 201, Washington, District of Columbia, 20005, USA.
authors.forename: Jurek G
authors.initials: JG
authors.lastname: Grabowski
keywords: Graduated driver licensing; Motor vehicle; Traffic