The Atlas and Database of Air Medical Services (ADAMS) is a web-based, password-protected, geographic information system containing data on air medical service main and satellite base helipads, communication centers, rotorwing aircraft, and major receiving hospitals for trauma in the United States. ADAMS initially was developed to provide the geographic information needed to support realtime, wireless routing of automatic crash notification (ACN) alerts from a crashed motor vehicle to the nearest air medical transport service and trauma center. This coupling of ADAMS and ACN technology to enhance emergency communications is expected to speed delivery of emergency medical care to crash victims and thereby reduce the deaths and disabilities caused each year. In addition to its planned use in ACN response, ADAMS is also a valuable data resource for trauma system research and homeland security applications. This article begins with an overview of ADAMS and briefly describes the features and rationale for its development. ADAMS is then used as a tool to assess the extent of air medical rotor-wing service coverage nationwide. Both geographic area and populations covered are determined for all 50 states. The correlation between increased air medical service coverage and reduced motor vehicle crash fatality rates is then examined.