I have ridden in some old (1950s) American passenger railroad cars. If I stretched my legs out full length, I could just barely touch the back of the seat in front of me. (I'm 5'8".) At that point, the person in front could recline their seat to their heart's content without causing any issues.
Oh, yes, there was an adjustable leg rest, too.
I'd love to be able to travel like that today (but of course I probably wouldn't be able to afford it...)
Amtrak still operates, and AFAIK the seat pitch is still the same. Prices are quite reasonable too: I just checked and a cross-country train ticket is about half the price of a plane ticket this time of year.
The big question is whether you're willing to spend 72 hours in one of those roomy coach seats (more like 80+ hours if you include connections). People fly because 5 hours of extreme discomfort is usually preferable to 72 hours of mild/moderate discomfort.
Oh, yes, there was an adjustable leg rest, too.
I'd love to be able to travel like that today (but of course I probably wouldn't be able to afford it...)