Majority of the plastics produced today are being mismanaged at the end of their life that ends up in either a landfill or incineration facility or leaked into the ocean or terrestrial environments. Plastics such as polyethylene terephthalate (PET) and polyolefins such as high-density polyethylene (HDPE), low-density polyethylene (LDPE), and polypropylene (PP) represent a significant portion of valuable plastic waste stream. The current plastic linear take-make-dispose system in the U.S. represents not just environmental threat but also an economic loss of ≈$10 billion/yr that ends up in landfills. Therefore, there is an urgent need to shift towards circular economy (CE) and close the loop on valuable plastic materials. However, the environmental, economic, and social impacts of implementing a plastics CE are still lacking, and tradeoffs among impacts at the systems level are still unknown. Our study presents a novel systems analysis framework for PET and olefin polymers in a CE that helps to understand different processes involved in a plastic waste supply chain. The environmental, social, and economic impacts of a plastic waste supply chain can be quantified using our framework. The first objective of our study was to identify LCA, TEA, process datasets, and knowledge gaps associated with waste plastic supply chain processes in the U.S. The second objective of our study was to develop an illustrative application of the framework by conducting a high-level systems analysis of PET bottles with closed-loop recycling. The systems analysis of PET bottles utilized a linear programming optimization method to assess the environmental impacts of plastics material flow in a CE. The key result from our optimization model indicated that both chemical and mechanical recycling processes are needed to achieve a true circular economy of PET bottles with the least greenhouse gas emissions, specifically reductions of 24% when compared with the linear economy.