Could this just be a result of the maturity of the North American economy? That would be consistent with the even smaller number of engineers graduating from Europe.

What I mean is that once an economy's growth slows, it seems that the need for engineers would diminish. China is going like gangbusters. Hence the focus on engineering and science.

While there might be some reduction from a slowing in growth, there is a certain floor level below which you cannot go without seeing infrastructure begin to crumble away. Ooops! I guess we already went past that point, didn't we? ;)
Could this just be a result of the maturity of the North American economy?

Normal capitolism, yes.

That would be consistent with the even smaller number of engineers graduating from Europe.

Why SHOULD someone who has brains and ability in applying those brains any way they wish go into a carreer track when other carrier tracks:

  1. get a %age of sales  (salespeople)
  2. Have TV shows about them  (lawyers)
  3. Recieve more pay, enough that you have Congress-Critters and a President call them overpaid (lawyers) or Warren Buffet calles them overpaid (MBAs as CEO)
  4. Most comapnies have tracks where MBA's and salesman can advance in title and pay, but others can not.

In a land where everyone feels they are a superstar, why would they want to limit themselfes income wise by being an engineer?

What I mean is that once an economy's growth slows, it seems that the need for engineers would diminish

When an economy produces nothing but deritive works, of course you don't need engineers.  Look at how well Hollywood and Disney does w/o engineers!