Massive quantities of hazardous substances are transported each day throughout the United States. While most arrive safely at their destination, uncontrolled releases of substances in transit do occur and have the potential of causing acute public health consequences for those individuals at or near the release. Data from 16 state health departments participating in the Agency for Toxic Substances and Disease Registry's (ATSDR) Hazardous Substances Emergency Events Surveillance (HSEES) system were analyzed to determine the public health consequences that occurred from actual releases in transit. Of the 9392 transportation events analyzed, 9.1% resulted in 2008 victims, including 115 deaths. The population groups injured most often were employees and the general public. The most common injury sustained was respiratory irritation. Evacuations were ordered in 5.5% of events effecting at least 63,686 people. Human error and equipment failure were the most common factors leading to events. These findings underscore the importance of job safety training, community planning, and effective emergency response to prevent adverse public health consequences from occurring or lessen their effect on the public. Published by Elsevier Science B.V.