The primary objective of this paper is to provide a comprehensive overview of state-of-the-art and state-of-the practice of ATCSs. The review focuses on the following major aspects: (1) commonly deployed ATCSs in the U.S. and other countries; (2) features and functions of different ATCSs; and (3) evaluation studies based on field tests or laboratory simulation. According to the published literature, the majority of system deployments resulted in significantly improved traffic operations compared to traditional time-of-day coordination plans. Besides, based on the number of system deployments, SCOOT has the largest world-wide deployments, while SCATS has the largest U.S. deployments. Considering the costs of the deployment, ACS Lite was the lowest, while SCOOT was the highest.