The US economy is about 1.5 times larger than the entire EU.
The US is over 2 times larger by land.
Population is about a quarter smaller. Still, Massachusetts has more people than Denmark, New York has the same as Romania, California has more people than Poland.
Our original founding documents cite "these united states", interestingly and very tellingly "these", not "the." States are their own entities, and you'd find many to have very different cultures and laws — probably the same level of variance you'd find in the EU.