In many cases, bridges were more influential in enabling road trips than interstates (or any highways) The Delaware Memorial Bridge allowed ferry-free driving from DC to New York in 1951. (And the NJ Turnpike, which opened the same year, is not a part of the federal Interstate system)

That's fair. I didn't address that because the GP post specifically said "interstate", and I didn't feel that the parent post was critiquing the broader point that lots of infrastructure projects between the 1930s and 1980s made travel more palatable, but specifically the association of the interstate system with the 1980s.