The US probably has enough scrap steel lying around to last for centuries. Talking out of my ass here, but you get the point.
That really isn't as true as it used to be...
Back in the day, I could run around to all my buddies and dig in their #1 pile and find awesome steel to work with, The last car trailer I made cost me under 200 bucks in steel (less the axles, which were also cheap and used).
When steel was cheap, everyone had great #1 laying all over the place...
I recently acquired a pair of 3500 lb drop axles, and have set out to do the same thing in this day... Nobody has any #1. Nobody. I will have to buy all the steel new. And needless to say, that project has been shelved indefinitely.