This paper describes the development and application of the CORFLO family of simulation models developed by the Federal Highway Administration. CORFLO is suitable for the assessment of the operational impact of incidents, reconstruction, bottlenecks, design alternatives, and control strategies in highway networks composed of freeways and surface streets. Also, CORFLO is suitable for many planning activities such as the assessment of network performance as a function of fluctuating origin-destination trips, regional control strategies, and traffic diversion strategies. This paper provides a brief summary of the CORFLO components, discusses issues related to the selection and use of these components based on the analysis to be undertaken, provides examples of possible CORFLO applications, and provides a summary of other development projects related to CORFLO.