From The Washington Post Wonk Blog (by Brad Plummer):
The best way to think of Amtrak is that it’s essentially two different train systems rolled into one. One system is quite successful, the other isn’t.
First, there are Amtrak’s shorter passenger routes that run less than 400 miles and tend to connect major cities. Think of the Acela Express in the Northeast, or the Pacific Surfliner between San Diego and Los Angeles. These 26 routes carry four-fifths of Amtrak’s passengers, or 25.8 million riders per year. And they’re growing rapidly. Taken as a whole, these shorter routes are profitable to operate — mainly because the two big routes in the Northeast Corridor earn enough to cover losses elsewhere.
Then there are Amtrak’s 15 long-haul routes over 750 miles. Many of these were originally put in place to placate members of Congress all over the country, and they span dozens of states. This includes the California Zephyr route, which runs from Chicago to California and gets just 376,000 riders a year. All told, these routes lost $597.3 million in 2012.
Brookings has a neat interactive tool that lets you scrutinize each of Amtrak’s routes, looking at how many passengers they carry and how much money they make (or lose) each year.