Preliminary Data Indicate That Booster Seat Laws Increase Child Safety Seat Use

NHTSA · 2007 · ROSA P / United States. Department of Transportation. National Highway Traffic Safety Administration

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Summary

This report evaluates the impact of Wisconsin’s 2006 booster seat law on child restraint usage among children aged 4 to 8. The legislation, enacted on June 1, 2006, mandated that children within this age range, weighing 40–79 pounds, and under 4 feet 9 inches tall, be restrained in booster seats. Prior to this law, children aged 4–8 could use either child safety seats (CSS) or standard safety belts. The study aimed to determine if this legislative change increased the use of appropriate restraints compared to a control state, Michigan, which had no specific booster seat law for this age group. The National Highway Traffic Safety Administration contracted with TransAnalytics, LLC, to conduct an observational survey using a convenience sampling method. Data collectors observed drivers parking at high-traffic sites, such as shopping centers and schools, in both Wisconsin and Michigan. Baseline data was collected in May 2006, and post-intervention data was gathered between September and October 2006. Observers recorded vehicle type, passenger demographics, seating positions, and restraint types after obtaining driver permission. Michigan served as a control because its laws required seat belts for children aged 4–16, without specific booster mandates, allowing for a comparison of trends in the absence of new legislation. The results indicated that while the specific increase in booster seat usage alone was not statistically significant in either state (rising from 40% to 45.9% in Wisconsin and 38.6% to 40.2% in Michigan), the overall pattern of restraint use changed significantly in Wisconsin (p<.02). In Wisconsin, the combined use of CSS and booster seats increased significantly from 48.6% to 57.7%, whereas Michigan saw a non-significant increase from 41.6% to 47.5%. Furthermore, the proportion of children inappropriately restrained (using only seat belts or no restraint) decreased by 9.1% in Wisconsin, compared to a 6% decrease in Michigan. The number of unrestrained children remained stable in Wisconsin but increased in Michigan. Most booster seats observed were backless models. The study concludes that Wisconsin’s booster seat law effectively motivated parents and caregivers to use age-appropriate restraints, as evidenced by the significant increase in combined CSS and booster seat usage and the reduction in inappropriate restraint practices. The lack of similar significant changes in Michigan supports the inference that the law drove these improvements. The authors note that while the convenience sampling limits generalizability, the data provides preliminary evidence that booster seat laws can enhance child passenger safety by shifting usage toward more protective restraint systems.

Key finding

Booster seat use among children aged 4 to 8 rose from 40.0% to 45.9% in Wisconsin after its booster seat law (versus 38.6% to 40.2% in comparison-state Michigan), an increase that was not statistically significant.

Methodology

field_study

Provenance

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Summary generated by qwen3.6-27b-prismaquant on 2026-06-10; verification: verified.

Topics

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• child passenger safety
• seat belt use