Summary: Over a year has passed since the terrorist attacks of September 11, 2001, realigned national priorities. Although most of the early attention following the attacks focused on airport security, emphasis on the other modes of transportation has since grown. Addressing transit safety and security concerns is complicated by the nature and scope of transit in the United States. About 6,000 agencies provide transit services, and each workday, 14 million Americans ride on some form of transit. Transit agencies face significant challenges in making their systems secure. Certain characteristics make them both vulnerable and difficult to secure. The high ridership of some transit agencies makes them attractive targets for terrorists but also makes certain security measures, like metal detectors, impractical. Another challenge is funding identified security enhancements. Despite the formidable challenges in securing transit systems, transit agencies have taken a number of steps to improve the security of their systems. Transit agencies visited by GAO were implementing strategies to improve both safety and security prior to September 11; however, the events of September 11 elevated the importance of security-related activity. Many agencies assessed vulnerabilities, provided additional training on emergency preparedness, revised emergency plans, and conducted multiple emergency drills. The federal government's role in transit security is evolving. Although the Federal Transit Administration has limited authority to oversee and regulate transit security, it launched a multipart security initiative and increased funding for its safety and security activities since September 11. In addition, the Aviation and Transportation Security Act created the Transportation Security Administration (TSA) within the Department of Transportation and gave it responsibility for transit security; however, TSA has yet to assume full responsibility for the security of any transportation mode other than aviation.