The constant struggle of Amtrak to get funding derives largely from the fact that not very many Americans use the rail system. Ridership is heavily centered in the Northeast, in the corridor between Boston and Washington where Tuesday's accident occurred. But more than that, ridership is unevenly distributed politically. Data from the National Association of Railroad Passengers shows the number of passengers that get on or off the train in any given congressional district, and reveals an obvious reason why Republicans might not be too concerned about funding the system.
Much of the heavy usage hugs the coasts; California's in-state system sees decent traffic. The Upper Plains states have seen steady usage in recent years thanks in part to the growth of the oil fields on the North Dakota/Montana border.
There are 184 congressional districts in which not one person got on or off a train in 2014. Sometimes, that was a function of there being a nearby station that saw many more passengers -- like the districts in Manhattan that don't include Penn Station. Sometimes, it's for the obvious reason that there are no rail lines operated by Amtrak (like in Hawaii). But the map above shows wide stretches of the country where rail service is simply not that commonly used. (There's an interactive version of that map below.)
Of those 184 districts, 116 are currently represented by Republicans. On average, ridership in Republican districts was about 41,000 in 2014 -- compared to 261,000 in Democratic districts.
Trains are more cost effective in more densely populated areas, and more densely populated areas in the United States tend to vote Democratic. There's another level of politics at play, of course; many conservatives consider the idea of a federally funded transportation program to be anathema. And since so few of their constituents actually use the system, there's little incentive to want to offer political support.
Tuesday's disaster could shift that thinking, just as it did after the crash in 2008. For some, like Vice President Biden, Amtrak is "a second family." For people on Capitol Hill, though, it's often more of an unwelcome and voracious guest.
Ridership by congressional district
This post has been clarified to explain that short-term Amtrak funding continued after the expiration of the 2008 bill.