Background and aims Alcohol‐impaired driving contributes to more than 10 000 fatalities in the United States each year. This research estimated the unique effect of enforcement intensity on reductions in alcohol‐impaired fatal crashes.

Design We collected data from 30 states (including the District of Columbia) that experienced the greatest changes in alcohol‐impaired fatal crashes from 1996 to 2006. Mixed‐model regression was used to examine the extent to which year‐over‐year changes in the intensity of impaired driving enforcement predicted year‐over‐year reductions of drivers killed in alcohol‐involved fatal crashes.

Setting Data from 30 states were obtained online.

Participants Aggregate state‐level data from a total of 279 state‐year combinations were analyzed.

Measures Our dependent measure was the ratio of drivers involved in fatal crashes with blood alcohol concentrations (BACs) ≥ 0.08 g/dl over drivers involved in fatal crashes with BACs = 0.00 g/dl. Per capita driving under the influence (DUI) arrests and traffic enforcement funding were the primary predictors. Covariates were estimated vehicle miles traveled (VMT); the proportional distributions of gender and racial/ethnic; geographic distribution; the proportion of drivers aged 21–34 years; median family income; and education level.

Findings Analysis revealed that DUI arrests per capita uniquely and significantly predicted reductions in the ratio of fatal crashes (β = –0.753, t (238) = 2.1, P < 0.05) after controlling the covariates. Exploratory analysis suggests the increase in arrest rates was associated with stronger reductions in urban versus rural settings.