Adaptive Traffic Control Systems (ATCSs), also known as real-time traffic control systems, adjust, in real time, signal timings based on the current traffic conditions, demand, and system capacity. Although there are at least 25 ATCS deployments in the United States, these systems may not be well understood by many traffic signal practitioners in the country. Their operational benefits are demonstrated, but there are still some reservations among the people in the traffic signal community. These systems are considered expensive and complex and they require high maintenance of detectors and communications. The study methodology included three sequential efforts. The first focused on the selection of ATCSs, which are typically deployed in the United States (and worldwide) and identification of ATCS agencies. The next effort undertaken was a literature review that gathered and reported information about ATCS operations and deployments from previous studies. Finally, two electronic surveys were conducted: a shorter e-mail survey for ATCS vendors and a longer website-based survey for ATCS users. Responses were obtained from 34 of 42 agencies in North America, an 81% response rate. Also, 11 responses from agencies in other countries were obtained. Municipal and county traffic operations agencies were the major contributors among the 45 agencies that responded to the survey.