The Highway Safety Information System (HSIS) is a multistate database that contains a large number of crash, roadway inventory, and traffic volume data for a select group of States. Currently, there are seven participating states, including California, Washington, Minnesota, Illinois, Ohio, North Carolina, and Maine. Past data are also available for Michigan and Utah. It is a cooperative endeavor funded by the Federal Highway Administration (FWHA), with data voluntarily provided by the participating states annually. All of the data files are stored in a relational database. The system is designed to provide data for research conducted in the general public interest, which is intended for publication in a scientific journal or other national publication. The database also serves as a good example of data management and collaboration among multiple states in the name of highway safety.