Testimony issued by the Government Accountability Office with an abstract that begins "Since its inception, the Transportation Security Administration (TSA) has focused much of its efforts on aviation security, and has developed and implemented a variety of programs and procedures to secure commercial aviation. More recently, TSA has taken actions to secure the nation's surface transportation modes. TSA funding for aviation security has totaled about $26 billion since fiscal year 2004, and for surface transportation security activities, about $175 million since fiscal year 2005. This testimony focuses on TSA's efforts to secure the commercial aviation system-- through passenger screening, air cargo, and watch-list matching programs--and the nation's surface transportation modes. It also addresses challenges remaining in these areas. GAO's comments are based on GAO products issued from February 2004 through April 2008 including selected updates obtained in February through April 2008."