Sometimes a local issue perfectly illuminates a larger national problem. Such is the case with the opposition of the New Jersey governor, Chris Christie, to construction of a new tunnel between his state and New York.

Christie argues that a state that is currently facing multibillion-dollar annual deficits cannot afford a huge new spending project that is already looking to be $5 billion overbudget. His critics argue that this tunnel is exactly the sort of infrastructure project that New Jersey needs if it’s to prosper in the decades ahead.

Both sides are right. But what nobody seems to be asking is: Why are important projects now unaffordable? Decades ago, when the federal and state governments were much smaller, they had the means to undertake gigantic new projects, like the Interstate Highway System and the space program. But now, when governments are bigger, they don’t.

The answer is what Jonathan Rauch of the National Journal once called demosclerosis. Over the past few decades, governments have become entwined in a series of arrangements that drain money from productive uses and direct it toward unproductive ones.