Amtrak—officially, the National Railroad Passenger Corporation—is the nation's primary provider of intercity passenger rail service. Amtrak is structured as a private company, but virtually all its shares are held by the United States Department of Transportation (DOT). Amtrak was created by Congress in 1970 to preserve a basic level of intercity passenger rail service, while relieving private railroad companies of the obligation to provide money-losing passenger service. Although created as a for-profit corporation, Amtrak has never made a profit; in this it resembles both the experience of the private-sector companies that preceded it and of intercity passenger rail operators in many other countries. During the 44 years from 1971 to 2015, federal assistance to Amtrak amounted to approximately $78 billion in constant 2015 dollars (see Appendix , Table A-1 ). Amtrak's approximately 20,000 employees operate trains and maintain its infrastructure. It carries around 31 million passengers annually, providing slightly less than 1% of total U.S. intercity passenger miles traveled by common carrier (see Table 1 ). The company operates approximately 44 routes over 21,000 miles of track. Most of that track is owned by freight rail companies; Amtrak owns about 625 route miles. The primary section it owns—the Northeast Corridor (NEC)—includes some of the most heavily used segments of track in the nation. The NEC is used not only by Amtrak's intercity trains, but also by regional commuter lines and some freight trains. By far, the greatest volume of NEC traffic consists of commuter trains, not Amtrak trains. Amtrak also operates corridor routes (covering distances under 400 miles) and long-distance routes (over 400 miles in length). Some of Amtrak's corridor routes are financially supported by states they serve. Amtrak also operates commuter service under contract with state and local commuter authorities in various parts of the country. Amtrak's expenses exceed its revenues each year. In FY2014, Amtrak's revenues totaled $3.2 billion, against expenses of $4.2 billion, for a net loss of $1.1 billion (see Table 2 ). That loss was covered by federal capital and operating grants which are made to Amtrak by the DOT. In recent years, these federal grants have often covered Amtrak's operating loss, with some funding left over. The federal grant in excess of the operating loss and debt service essentially represents the funding Amtrak has available to undertake activities outside of keeping its trains running and covering depreciation of its assets, such as improving its infrastructure and bringing station platforms into compliance with Americans with Disabilities Act requirements. Amtrak's federal funding is primarily provided within the Department of Transportation's appropriation. The Administration requests funding for Amtrak each year as part of its DOT funding request. Amtrak also submits a separate appropriation request directly to Congress each year; typically, that request is larger than the Administration request. Table 3 shows the difference in the requests that were submitted for FY2016. In recent years, Congress has typically divided Amtrak's grant into two categories: operating and capital grants. Roughly, the operating grant can be thought of as relating to Amtrak's annual cash loss, and the capital grant as relating to Amtrak's depreciation loss, as well as an amount for Amtrak debt repayments. Amtrak funding was authorized through FY2013 in the Passenger Rail Investment and Improvement Act of 2008 (Division B of P.L. 110-432 ). Table 4 shows the funding authorized for Amtrak in that act and proposed in H.R. 749 , the Passenger Rail Reform and Investment Act of 2015, as passed by the House of Representatives, and the actual amount of funding provided to Amtrak through appropriations. During the most recent reauthorization of federal surface transportation programs, the Administration and the House and Senate proposed to include Amtrak in surface transportation reauthorization legislation, but the version enacted in 2012, covering the period FY2013-FY2014, did not include Amtrak. Amtrak is able to cover about two-thirds of its total costs from its passenger-related revenues. That leaves a portion of its operating (i.e., cash) expenses—and virtually all of its capital expenses, including depreciation—to be covered by outside funding, primarily federal funding. The federal grants Amtrak receives have, in recent years, typically been enough to cover its annual loss with a little left over to go toward new projects. Amtrak's requests for federal funding are not likely to shrink in the future. It reports a backlog of capital maintenance of many billions of dollars, and says this backlog grows larger each year because the amount of money available for capital repairs is not enough to keep up with the annual maintenance needs. The stability, or predictability, of Amtrak's federal funding levels is a perennial issue. Like other railroad companies, Amtrak's operations require extensive spending on the maintenance and improvement of track, rolling stock, signaling systems, and other facilities. Roughly half of Amtrak's budget comes from federal funding appropriated on a year-to-year basis by Congress. The Department of Transportation's Inspector General has noted that the lack of long-term funding "has significantly affected Amtrak's ability to maintain safe and reliable infrastructure and equipment, and increased its capital program's annual cost." Amtrak has long sought some measure of certainty in its level of federal funding. Amtrak authorization legislation has often authorized federal funding over a period of several years. But those authorization levels are not binding on appropriators. By contrast, the authorizations for highway and transit programs in surface transportation authorization legislation are typically in the form of a special form of budget authority (contract authority) drawn from a trust fund, which provides more predictable funding. There have been proposals to create a trust fund for Amtrak, in order to provide a greater level of stability to Amtrak's federal funding. Such efforts have faced both a policy challenge and a practical challenge. The policy challenge is related to the issue of funding uncertainty; one reason that Amtrak's federal funding is uncertain is that some Members of Congress are opposed to Amtrak receiving federal funding, and therefore oppose providing a more predictable level of future federal funding. The practical challenge is to identify where the revenues for an Amtrak trust fund would come from. The level of federal funding that Amtrak receives could not be provided solely from a tax on Amtrak passengers; to provide the same level of federal funding Amtrak currently receives, the tax on passengers would have to be roughly two-thirds of the current ticket cost. Such a large cost increase would likely reduce ridership, so the tax would probably not raise the desired amount of revenue. Another means of providing a reliable funding source might involve setting aside money from the existing Highway Trust Fund (HTF). This approach has met with opposition on the basis of both principle (the argument being that the HTF's revenue comes from road users, mainly through motor fuels taxes, and should be used for road-related purposes) and practicality (the revenues flowing into the HTF are far below the level required to maintain the existing level of federal highway and transit spending provided by the fund). In recent years, the shortfall in revenues to the highway trust fund, compared to its level of expenditures, has led Congress to transfer significant sums from the general fund of the Treasury to maintain the trust fund's solvency: $34.5 billion during the period FY2008-FY2010, and another $18.8 billion during the period FY2013-FY2014. Joseph Boardman, the CEO of Amtrak, has pointed to these transfers as undermining the principal argument against providing HTF funding to Amtrak, since a significant portion of HTF funding now comes from general revenues rather than highway-related taxes. He has urged that intercity passenger rail be eligible for funding from the portion of HTF funds coming from general fund revenues. Amtrak owned no infrastructure at the time of its creation. It was structured as a contracting agency, and Amtrak trains were operated by private railroads over tracks they owned. Several years later, as Congress was dealing with the bankruptcy of the Penn Central Railroad, Congress decided that Amtrak would receive much of the trackage owned by the Penn Central in the 450-mile corridor running from Washington, DC, north through Philadelphia and New York City to Boston, along with shorter lines serving Harrisburg, PA, and Springfield, MA. The Northeast Corridor traverses one of the most densely populated and economically important corridors in the world and carries over 259 million passengers annually (the vast majority aboard trains run by regional commuter operators). The NEC also carries freight trains run by private railroads. (Amtrak also inherited 96 miles of track in Michigan, and controls short lengths of track in other locations.) Portions of the NEC are well over a century old, and the alignment was laid out at a time when the top speed of trains was much less than is possible today. This has caused problems for Amtrak's efforts to improve service on the NEC. Amtrak has identified three general issues: a large backlog of capital projects needed to bring the NEC to a state of good repair; limits on the number of trains that can operate on the NEC, especially due to bottlenecks at tunnels; and increasing demands for service on the NEC, including service by commuter operators. The NEC is Amtrak's flagship corridor, with its fastest service. The Acela attains speeds of up to 125 mph on the southern section between Washington, DC, and New York City, and up to 150 mph (briefly) on the northern section between New York City and Boston.