The state-of-the-practice in transportation modeling and analyses has long centered on methods that include using the four-step travel demand forecasting process and the highway capacity manual. Whereas these methods have served well in the past, there is need to better address emerging transportation issues such as emissions or assessing the benefits of intelligent transportation systems applications. At the same time, there is also need to address these emerging issues at a system wide lével as opposed to the traditional individual application level. Traffic micro-simulation models provide a great tool for these purposes. Traffic micro-simulation models enable transportation design, operations and planning analyses through simulation of various scenarios at a detailed, second-by-second level. This paper focuses on the process of developing a large-scale state of the art regional micro-simulation model for the Nebraska State Highway System. Specifically, the model is developed to serve as a platform on which to perform coordinated freeway and arterial analyses of the I-80 corridor between the cities of Lincoln and Omaha, Nebraska. The model is built with the VISSIM micro-simulation package and is implemented on approximately 100 miles (160.9 kilometres) of freeway including the adjoining on- / off-ramps as well as 116 signalized intersections within the vicinity of the freeway. The resulting model involves 9,120 origin-destination (OD) pairs, 794 nodes, and 12,809 links and connectors. Particular emphasis is placed on model development and implementation issues including challenges associated with data collection, OD demand estimation as well as model calibration and validation using ITS data.