The purpose of the study documented in this report was to determine how transportation planning for special events is best conducted when mobility considerations are subordinated to security priorities. The subject of this study was the 2004 Democratic National Convention (DNC), held in Boston, Massachusetts, from July 26 through July 29, 2004. This event was designated a National Special Security Event by the U. S. Department of Homeland Security. This designation established the U.S. Secret Service as the lead agency because security measures would take precedence over other actions, such as providing mobility to delegates and residents. The role of transportation agencies was to implement procedures that would accommodate the security measures developed for the convention.