There is also the problem of diminishing returns. Paving the roads and later upgrading them to highways improved the transportation capabilities a lot. I am at a loss as to what you would upgrade to now (unless you want to make it greener, but environmentalism doesn't improve the economy).
> I am at a loss as to what you would upgrade to now
There are upgrades to be had: HSR (where it makes sense), more modern air traffic control, intelligent transport systems, multimodal facilities, high-speed internet, power generation (green or otherwise), smart grid, flood contro, seismic refits, etc.
But we don't even need to discuss upgrading the infrastructure, most of what we have now is subpar because of decades of deferred or non-existent maintenance. We will need to spend billions just to get our existing systems up to par,
We're getting far afield, but the problem with American education isn't a lack of funding. Look at the slope of a graph of education funding over time, and you'll see that it would be difficult to pump cash in any more quickly than we already have -- and to no avail.
