Abstract: Kotamobagu city is a city which is established as a result of proliferation of region. The proliferation of region is aimed at improving public services for community welfare, including road network infrastructure. This study aims to examine the correlation between road network infrastructure and proliferation of region, in this case the density of the road network after the proliferation of region. The method used to examine the density of the road network was by overlaying maps of the road network in 2000 and 2013. The results of map overlay were calculated using a simple statistical tools in Ms. Excel 2010 and the results were calculated using the formula of road network density and was analyzed descriptively. The results of overlay map of the road network density in 2000 and 2013 indicated the existence of the highest density of the road network in Kotamobagu city spatially after the proliferation of region. The highest density of the road network was in the city center and several surrounding villages. The road network increased in all the main roads spatially in Kotamobagu City after the proliferation of region. The road network density and the improvement of the road network in Kotamobagu City were affected by the proliferation of region.