One of the key challenges in securing the U.S.- Mexico border is deterring the smuggling of illicit goods and humans between the ports-of-entry (POEs). Inconsistent levels of fencing, favorable terrain, and tacit knowledge of specific pathways have provided traffickers with preferred corridors of illicit transit strengthened with the success of each attempt. Individuals and networks trafficking people across the Arizona-Mexico border also face additional incentives and costs given the requirement to maintain physical control of individuals once they have crossed into the United States and move them to drop houses within major cities of Arizona. These additional decision factors could alter the likely pathways as well as potential destination points for human traffickers in Southern Arizona, and influence future efforts to deter or disrupt trafficking operations. In order to understand the probable pathways by which human traffickers transit into Arizona, START will employ their TRANSIT program to model the most probable routes for human trafficking from transfer points in Northern Mexico into Arizona. Network modeling will allow for the identification of intermediate chokepoints where multiple probable routes of trafficking converge as well as likely entry points between the POEs. In addition, the project will utilize Stochastic Network Interdiction Problem (SNIP) models to estimate enforcement effects on potential trafficking chokepoints, highlighting diversionary efforts by adversaries to utilize alternative pathways into the United States. The overall pilot project will highlight the most probable routes, the opportunities for interdiction, and estimations of displacement or diffusion of probable routes based on simulated enforcement efforts on trafficking chokepoints along a 200-mile section of the U.S.-Mexico border in Arizona. Results will also be calculated for human smuggling efforts to compare contrasting set of pathways which share some similar decisions as human traffickers, but who differ in theoretically and operationally-relevant ways.