At the Economist‘s Democracy in America blog, R.A. makes some good points in favor of skepticism on the question, riffing on Robert Fogel’s research on the economics of the railroad. Excerpt:
Highway construction generated some positive effects and some negative effects. We tend to focus on the positive effects and remark on how constrained the economy might have been without a highway boom. But absent a highway boom something would have been built and markets would have optimised to that something. It’s not clear that the savings from highways are so substantial that the American economy is clearly better off as a result of the system’s construction.