Dates may be represented may ways. Intersection Magic can handle most of them. This article describes which formats are supported and will be properly converted by the program.
The California Highway Patrol (CHP) maintains the crash records that you use as SWITRS data. In January of 1998 they modified the format which had been used for many years. The format was changed to add the century to any dates in the data file. This makes the data y2k compatible. This requires special treatment of SWITRS data by Intersection Magic.