Recent advancements in the Vehicle Routing Problem have increasingly focused on incorporating environmental concerns in the transportation planning process. Traditionally, transportation optimization efforts centered on minimizing costs, time, or distance. However, as sustainability and environmental cost control have gained importance, logistics companies and retailers are progressively adopting environmentally sustainable practices. This paradigm shift has resulted in the development of the Pollution-Routing Problem (PRP), which seeks to align economic and environmental objectives in transportation. Despite the substantial body of research on PRP, a comprehensive systematic review of its methodological developments has been lacking. This review chapter identifies current gaps by mapping the progression of the PRP literature since its introduction in 2011, classifying studies based on the methodologies utilized over time. Furthermore, this chapter highlights several promising research directions, offering a framework for future exploration in this domain.