Mabalacat City prepares for the influx of investors due to the decentralization of Metro Manila in which investors opt to locate in Clark Freeport Zone. More locators would mean greater transport demand; may it be person trips or cargoes. Being a national highway and serving as an alternative non-tolled route, Mac Arthur Highway is prone to having through traffic. This study aims to develop a GIS-based road network map of Mabalacat City, Pampanga to analyse traffic congestion with use QGIS Overlay and Proximity analysis to identify the most congested areas, determine the Level of Service of the main corridor, and suggest possible solutions. After performing proximity analysis, the researcher found out that the most congested junctions were the NLEX Extension/MNR and the Velasquez St./MNR Intersection. With the conducted of peak hour volume survey, corresponding values to V/C ratio all fell under level F. This means the government must take action to mitigate the traffic congestion along the Mabalacat main corridor.