Mass media and industrialization have definitely caused some convergence, but in the context of an America where it took more than a day for some intra-state trips this made sense. There's still definitely a lot of regional pride and some differences, most notably in Texas, which is rather unique in its mythology because it existed as a country for a short period and fought an independence war.

The US when it formed was probably more aligned with what the EU is today. That original setup was very impractical so they reformed into the current US with the Constitution in 1789.