AMERICA has by far the largest rail network in the world, with more than twice as much track as China. But it lags far behind other first-world countries in ridership. Instead of passengers, most of America's massive rail network is used to carry freight. Why don't Americans ride trains? Rail ridership is usually measured in passenger-kilometres—one passenger-kilometre represents one passenger travelling one kilometre. One 1,000-person train travelling 1,000 kilometres would on its own account for a million passenger-kilometres. Yet American railroads accounted for just 17.2 billion passenger-kilometres in 2010, according to Amtrak, America's government-backed passenger rail corporation. In the European Union, railways accounted for nearly 400 billion, according to International Union of Railways data. When you adjust for population, the disparity is even more shocking: per capita, the Japanese, the Swiss, the French, the Danes, the Russians, the Austrians, the Ukrainians, the Belarussians and the Belgians all accounted for more than 1,000 passenger-kilometres by rail in 2011; Americans accounted for 80. Amtrak carries 31m passengers per year. Mozambique's railways carried 108m passengers in 2011.

There are many reasons why Americans don't ride the rails as often as their European cousins. Most obviously, America is bigger than most European countries. Outside the northeast corridor, the central Texas megalopolis, California and the eastern Midwest, density is sometimes too low to support intercity train travel. Underinvestment, and a preference for shiny new visions over boring upgrades, has not helped. Most American passenger trains travel on tracks that are owned by freight companies. That means most trains have to defer to freight services, leading to lengthy delays that scare off passengers who want to arrive on time. Domestic air travel in America is widely available, relatively cheap and popular. Airlines fear competition from high-speed rail and lobby against it. Travelling by cars is also popular. Petrol is cheaper than in Europe (mostly because of much lower taxes). Road travel is massively subsidised in the sense that the negative externalities of travelling by car, including the release of carbon dioxide and other greenhouse gases, are not fully offset, and most major highways—which cost tens of billions to maintain—are still free of tolls. And finally, Barack Obama's embrace of high-speed rail has heightened a political battle over rail that doesn't exist quite in the same way in other countries (although the fraught debate over high-speed rail in Britain comes close). Opposition to rail is now often seen as essentially conservative, and Republican governors oppose rail projects to boost their conservative image.

America's national-level politics are unlikely to become more functional in the near term. So all this leads to an inevitable conclusion: what happens with California's planned high-speed rail system matters a lot. If it is completed, works and is popular—all of which are uncertain—other states will undoubtedly take note. If California's high-speed dream fails, it may be a long time before America has true high-speed service. And by that point, America may be ready to put in a call to Elon Musk. Hyperloop, here we come!