Accident Analysis and Prevention 37 (2005) 1114–1120 Getting Americans to buckle up: The efficacy of state seat belt laws David J. Houston a,∗ , Lilliard E. Richardson Jr. b a Department of Political Science, 1001 McClung Tower, University of Tennessee, Knoxville, TN 37996-0410, USA b Truman School of Public Affairs, 105 Middlebush Hall, University of Missouri-Columbia, Columbia, MO 65211-6100, USA Received 24 May 2005; received in revised form 24 May 2005; accepted 9 June 2005 Abstract Annual state observed safety belt use rates over the period 1991–2001 are examined using time-series cross-section regression analysis. It was found that seat belt laws are associated with higher use rates and that the enforcement provision matters. Primary states experience belt use rates that on average are 9.1 percentage points higher than their secondary counterparts. In addition, the level of the fine imposed by statute has an effect on safety belt use apart from that attributable to the enforcement provision. The current median fine of $25 is associated with an additional 3.8 percentage points increase in belt use. To further increase safety belt use, it is recommended that states adopt primary enforcement and impose fines of at least $50 for violating a seat belt law. © 2005 Elsevier Ltd. All rights reserved. Keywords: Seat belt use law; Seat belt use rate; Primary enforcement; Secondary enforcement; Fine; Evaluation 1. Introduction Safety belt use rates have increased over the past 20 years since the first seat belt law was adopted by New York in 1984. National use rates were estimated to be about 17% in 1983 (National Highway Traffic Safety Administration, NHTSA, 1992) and had risen to 75% by 2002 (Glassbrenner, 2004). Even so, significant variation exists among the states as in 2002 the State of Washington had the highest observed use of 93% while Massachusetts had the lowest at 51% (Glassbrenner, 2003). Although seat belt usage has increased substantially over the past 20 years, considerable progress is needed to reach the goal of 90% by 2005 as set by the Presidential Initia- tive on Seat Belt Use in 1997 (NHTSA, 1997). To increase belt use, the Federal government has encouraged states to adopt stronger mandatory use laws (NHTSA, 1997, 2004). NHTSA encourages states with secondary enforcement laws to upgrade to primary enforcement. States also are encour- aged to increase fines for violation of the law and to expand coverage to every occupant in a motor vehicle. ∗ Corresponding author. Tel.: +1 865 974 5278; fax: +1 865 974 7037. E-mail address: dhouston@utk.edu (D.J. Houston). Previous research on the effect of seat belt laws has focused almost exclusively on the enforcement provision of these statutes. This study examines not only the enforcement provision but also the effect of statutory fines and seat cov- erage on state observed use rates for the period 1991–2001. 2. Effectiveness of state seat belt laws New Hampshire remains the only state without a law that mandates adult belt use. Three key provisions characterize the strength of these state laws: primary versus secondary enforcement, the monetary fine imposed for violating the law, and all seat versus front seat coverage. Substantial variation exists among the states in terms of these three key provisions. In 2004, 20 states and the District of Columbia provide for primary enforcement while 29 state laws authorize only secondary enforcement. In terms of cov- erage, all adult passengers are required to use a safety belt in 17 states and the District of Columbia, while only front seat occupants are required to do so in the other 32 states (Insurance Institute for Highway Safety, IIHS, 2004). The minimum statutory fine ranges from a low of $10 to a high of $75 with the median being $25 (IIHS, 2004). It is important to point out that the full cost of a seat belt violation is higher than 0001-4575/$ – see front matter © 2005 Elsevier Ltd. All rights reserved. doi:10.1016/j.aap.2005.06.009