During the year of operations, three full-time deputies of the McHenry County Sheriff's Department spent 3,859 hours patrolling the high-accident locations selected for concentrated enforcement. More than 3,240 citations and 708 warnings were issued. Hours of increased patrol were distributed to the locations in proportion to the frequency of accidents that had previously occurred in each location. Citations, however, were not issued in proportion to the causes of accidents; speeding violations constituted 59 percent of those cited, while county records attributed only 20 percent of accidents to this violation. An average contact rate of one violator per hour was attained which is comparable with similar projects on rural roads and indicates that the police were active and visibly enforcing traffic laws. Reduction of traffic accidents at the patrolled locations from predicted levels was statistically significant at the 99 percent confidence level. A significant reduction also occurred in the number of fatal and personal injury accidents that occurred during the project year. Traffic accidents occurring during good weather were reduced significantly compared to averaged data from the 3 previous years. The project was particularly successful during good weather conditions. Public awareness was an integral part of the project, with publicity underlining the highway safety purpose of the project. A benefit-cost ratio of approximately 12 to 1 was calculated using National Safety Council cost estimates for accidents. Statistics are provided. (Author abstract modified)