An unusual view of how the U.S. has changed

A poster on another site writes: 

Some years ago I acquired a collection of Scientific American magazines from the mid-50s through the mid-60s. The ads are fascinating--most for engineering firms, machine shops, and electronic and chemical companies.
     Some companies were large, but many more were small local businesses across the country that actually designed and built things. They proudly touted their products and skills, and brimmed with optimism that they were improving the human condition through science and technology.
     Most of those companies seem to be gone now. It was a different world then, and a different America.

One sees the same thing in virtually all technical journals of that age.  If you want to see how much America has changed in a few decades, browse through some tech journals at your local university library.  It's a sobering experience.