Drunk driving affects thousands of lives every year. It is a dangerous behavior that continues to be a national, state, and local problem. In 2006, there were 17,602 people killed in the United States in alcohol related motor vehicle accidents. One purpose of this study was to examine blood alcohol concentration (BAC) and percent of drivers with a BAC over the legal limit among those pulled over and tested for the presence of alcohol in Riverside and Imperial counties. The data was analyzed to identify patterns or shifts that have occurred over the 5 year period of study. An analysis of predictors of BAC over the legal limit was also conducted. The data from this study was obtained from the California Department of Justice, Bureau of Forensic Services, Riverside Criminalistics Laboratory. Data was collected from January 1, 2004 to December 1, 2008 and consisted of 46,635 records of drivers who had a BAC greater than 0.00. Six factors were evaluated as predictors of drivers being over the legal limit and they were: month and year of arrest, age, county, type of test, and whether the stop was made on a holiday or not. Stepwise logistic regression was performed to select the terms used in the model. Age, year, and type of test were the used in the final model. The results indicated that the odds of a driver being over the legal limit were 3.8 times greater in driver's ages 25-49 compared to those under 20. In addition, drivers 50-59 were 3.4 times more likely to be over the legal limit than those under 20. Drivers who had a blood or urine sample collected were roughly 1.3 times more likely to be over the legal limit than those who had a breath test performed. Drivers who were tested in 2007 were 1.3 times more likely to be over the legal limit than those tested in 2004. In total, 93% of drivers in this study were over the legal limit and the mean BAC was 0.15 which is almost twice the legal limit. It is estimated that three out of every ten Americans will be involved in an alcohol-related crash during their lifetime. Drunk drivers cost the American public approximately 114 billion dollars each year in court time, medical expenses, legal fees, and other expenses. By using predictor variables for determining populations at risk, prevention interventions can be targeted toward high risk populations in an effort to reduce drunk driving and save lives.