Simulation is a useful and cost effective tool for evacuation planning. However, extensive data collection and preparation is necessary to build a traffic evacuation simulation model that can closely replicate real life conditions. In a community-wide evacuation process during an emergency, which covers hundreds of miles, input data related to simulation of traffic evacuations include (1) Traffic and roadway geometry, (2) Geographic distribution of the affected area, (3) Travel demand modeling, and (4) Behavioral analysis of potential evacuees. This paper presents a framework for preparing simulation inputs and ultimately developing a simulation model. Brief excerpts from a case study on the evacuation of Charleston, South Carolina are also included. An accurate input analysis is very important to the success of a simulation project since without correct input data, the output of a simulation cannot contribute to more effective decision making. This paper presents a simple and efficient methodology for data preparation regarding a large scale city evacuation simulation involving long distance trips.