You're oversimplifying. The original rail lines in nyc were largely built and run by private companies. Most of these lines were (and many still are) above grou

You're oversimplifying. The original rail lines in nyc were largely built and run by private companies. Most of these lines were (and many still are) above ground. Later there was a lot of consolidation - smaller lines were bought up by larger lines that connected them together - prior to the era in which the government subsidized and then came to control the whole system. Part of why the subway system still works pretty well today is that these original routes - connecting the heart of the city to the outer boroughs - were designed to go where the demand was so they could pay back the investment quickly. Whereas when rail lines are built with too much government control often they end up ignoring or even deliberately avoiding the most useful and profitable routes in favor of politically motivated ones. (For instance, the monorail in Las Vegas didn't initially go to the airport because the cab companies don't want it to. And buses in San Francisco go through chinatown to please the chinatown merchants rather than the commuters trying to get past that area.) BTW, you "private-sector" build a subway the same way you do an oil pipeline or a transcontinental railway (eg, Hill's Great Northern Line http://en.wikipedia.org/wiki/Great_Northern_Railway_%28U.S.%29 http://en.wikipedia.org/wiki/Great_Northern_Railway_%28U.S.%... )