This paper describes the usage of a regional travel demand model and an extracted mesoscopic sub-simulation model in tandem to model and observe the traffic impacts of an off-hour delivery (OHD) program. The study is based on OHD-participation behavioral data for the New York City borough of Manhattan, with traffic impacts measured throughout the New York metropolitan region. Analysis is conducted to determine the effectiveness and impacts of the scenarios modeled; focusing on the changes predicted by the traffic models, with link travel time and speed changes as the key measure of output. The results from both models are compared and analyzed, and a discussion on the usage of these models for this purpose is presented.