The Erie Canal. Hoover Dam. The Interstate Highway System. Visionary public projects are part of the American tradition, and have been a major driver of our economic development.

And right now, by any rational calculation, would be an especially good time to improve the nation’s infrastructure. We have the need: our roads, our rail lines, our water and sewer systems are antiquated and increasingly inadequate. We have the resources: a million-and-a-half construction workers are sitting idle, and putting them to work would help the economy as a whole recover from its slump. And the price is right: with interest rates on federal debt at near-record lows, there has never been a better time to borrow for long-term investment.

But American politics these days is anything but rational. Republicans bitterly opposed even the modest infrastructure spending contained in the Obama stimulus plan. And, on Thursday, Chris Christie, the governor of New Jersey, canceled America’s most important current public works project, the long-planned and much-needed second rail tunnel under the Hudson River.

It was a destructive and incredibly foolish decision on multiple levels. But it shouldn’t have been all that surprising. We are no longer the nation that used to amaze the world with its visionary projects. We have become, instead, a nation whose politicians seem to compete over who can show the least vision, the least concern about the future and the greatest willingness to pander to short-term, narrow-minded selfishness.