Federal assistance to public transportation is provided primarily through the public transportation program administered by the Federal Transit Administration (FTA). The federal public transportation program was authorized through FY2014 as part of the Moving Ahead for Progress in the 21 st Century Act (MAP-21; P.L. 112-141 ) and extended through May 31, 2015, as part of the Highway and Transportation Funding Act of 2014 ( P.L. 113-159 ). MAP-21 made significant modifications to the public transportation program. While maintaining the previous funding level, MAP-21 simplified the structure of the public transit program by eliminating some programs and consolidating others, recast some discretionary programs as formula programs, strengthened FTA's role in safety oversight, and introduced performance management into the planning process. This report highlights some of the issues likely to arise as Congress considers further extension of MAP-21 or reauthorization. It begins with an overview of public transportation, its funding, and the federal public transportation program as currently authorized. Public transportation (also known as public transit, mass transit, and mass transportation) is defined in federal law (49 U.S.C. §5302) as regular, continuing shared-ride surface transportation services that are open to the general public or open to a segment of the general public defined by age, disability, or low income; and … does not include—(i) intercity passenger rail transportation …; (ii) intercity bus service; (iii) charter bus service; (iv) school bus service; (v) sightseeing service; (vi) courtesy shuttle service for patrons of one or more specific establishments; or (vii) intra-terminal or intra-facility shuttle services. The main forms of public transportation are bus, heavy rail (subway and elevated), commuter rail, light rail, paratransit (also known as demand response), and ferryboat. About 51% of public transportation trips are made by bus, 35% by heavy rail, 5% by commuter rail, and 5% by light rail (including streetcars). Paratransit accounts for about 2% of all public transportation trips, and ferries less than 1%. Transit ridership dropped precipitously at the end of the Second World War due to a number of interrelated factors, particularly rising incomes, growing automobile availability and use, and residential and employment decentralization. Despite the longer-term downward trend, ridership has risen over the past two decades from a low of 7.8 billion trips in 1995 to 10.6 billion trips in 2012. Consequently, ridership is at a level not seen since the late 1950s, although the population has grown by about 140 million people since then. Public transportation accounts for about 2% of all daily trips and about 5% of trips to and from work (commute trips). Ridership is heavily concentrated in a few large cities and their suburbs. About 75% of all public transportation trips are made in 10 large urbanized areas: New York, Los Angeles, Chicago, Washington, San Francisco, Boston, Philadelphia, Seattle, Miami, and Atlanta. The New York City urbanized area alone, including parts of New Jersey and Connecticut, accounts for about 4 of every 10 public transportation trips nationally. Almost a third of workers in the New York metropolitan area commute by public transportation, but in only four others (San Francisco, Washington, Boston, and Chicago) does the share exceed 10%. Major federal involvement in public transportation dates to the Urban Mass Transportation Act of 1964 (P.L. 88-365). In the mid-1960s, with much lower ridership than existed at the end of World War II and mounting debts, many private transit companies were reorganized as public entities, and federal funding was initially used to recapitalize them. Today, most federal support still goes for capital projects, but the program has evolved to support operational expenses in some circumstances, as well as safety oversight, planning, and research. MAP-21 authorized $10.6 billion for the federal public transportation program in FY2013 and $10.7 billion in FY2014. Funding made available for those years in appropriations bills was slightly higher ( Table 1 ). The Highway and Transportation Funding Act of 2014 extends the FY2014 authorized funding level though May 31, 2015. Excluding funding provided in the American Recovery and Reinvestment Act (ARRA; P.L. 111-5 ) and the Disaster Relief Appropriations Act, 2013 (DRAA; P.L. 113-2 ), public transportation program funding has been between $10 billion and $11 billion since 2009 ( Figure 1 ). ARRA provided an extra $8.4 billion in FY2009. DRAA provided $10.9 billion in FY2013 for FTA's Public Transportation Emergency Relief Program in response to Hurricane Sandy, particularly to repair the damage to the public transportation systems of New York and New Jersey. About 5% of the $10.9 billion, approximately $545 million, was subject to sequestration, leaving about $10.3 billion for emergency relief. Typically, about 80% of federal public transportation program funding comes from the mass transit account of the highway trust fund and 20% comes from the general fund of the U.S. Treasury. It should be noted, however, that the distinction between money from the highway trust fund and money from the general fund has become artificial to an extent, in that Congress authorized a $4.8 billion transfer of general fund money into the mass transit account of the highway trust fund in FY2010 and another $4.0 billion transfer in FY2014. Moreover, ARRA and DRAA funding for public transportation came exclusively from the general fund. Public transportation also receives support through provisions that make it an allowable use of some federal highway funds. Most funds "flexed" to transit programs come from the Surface Transportation Program (STP) and the Congestion Mitigation and Air Quality Improvement Program (CMAQ). Flexing is at the discretion of state and local decision-makers, so the amount transferred from highways to public transportation can vary widely from year to year. About $1 billion was flexed in FY2009, whereas $2.4 billion was flexed in FY2012. The percentage of highway funds transferred to transit has ranged from about 2.0% in FY1998 to about 5.7% in FY2012. The Transportation Investment Generating Economic Recovery (TIGER) program has been another source of federal funding for public transportation over the past few years. Enacted initially as part of ARRA, the TIGER program has been funded in five subsequent appropriations bills. Funding, appropriated from the general fund, was $1.5 billion in FY2009, $600 million in FY2010, $527 million in FY2011, $500 million in FY2012, $474 million in FY2013 (after an across-the-board rescission and sequestration), and $600 million in FY2014. Of the $584 million awarded in FY2014, for example, $187 million (32%) went to transit projects. Special-needs paratransit is another area in which funding is available from the federal government outside the public transportation program. Special-needs paratransit, also known as demand response or dial-a-ride, is non-fixed-route service for people with disabilities and the elderly, and typically involves the use of small buses, vans, or passenger cars. The Government Accountability Office (GAO) has identified 73 federal programs in seven federal agencies other than the Department of Transportation (DOT) that fund special-needs transportation services. Although GAO could not estimate the transportation spending in all of these programs, in 21 programs for which data were available transportation funding amounted to $2.3 billion in FY2010. This compares with FTA spending on special-needs paratransit in the same year of about $270 million. The costs of providing public transportation service fall into two main categories, operating expenses and capital expenses. Operating expenses include vehicle operation and maintenance, maintenance of stations and other facilities, general administration, and purchase of transportation from private operators. Capital expenses are related to the purchase of equipment, such as buses, rail lines, and rail stations. In general, federal public transportation programs allow an 80% maximum federal share for capital projects and a 50% maximum share for operating expenses. Operating costs account for about two-thirds of all costs for public transportation and capital expenditures for about one-third. Fares and other operating revenues cover only one-quarter of the total cost, with the remainder provided by federal, state, and local governments. The federal government supports less than 10% of operating expenditures, but more than 40% of capital expenditures ( Table 2 ). There are six major funding programs administered by FTA: (1) Urbanized Area Formula; (2) State of Good Repair (SGR); (3) New Starts; (4) Rural Area Formula; (5) Bus and Bus Facilities Formula; and (6) Enhanced Mobility of Seniors and Individuals with Disabilities. In addition, about 5% of the public transportation program funding is authorized for the Growing States and High Density States Formula ($519 million in FY2013 and $526 million in FY2014). This is not a program per se, but provides additional money to some places and is distributed through the Urbanized and Rural Area Formula Programs ( Figure 2 ). The Growing States apportionment is based on forecasted state population growth, and the High Density apportionment is to states with a population density greater than 370 persons per square mile. Funding for all of these programs, except New Starts, comes from the mass transit account of the highway trust fund. New Starts funding comes from the general fund. There are also several much smaller programs (see the Appendix for a full listing).