US's very few distinctive local accents

You're joking, yes? Maybe you've spent too much time on our West Coast, where nobody has a distinctive accent because they're all transplants. But in the Eastern and Central time zones, you'll find a plethora of distinctive accents (though one might argue some aren't worth preserving, like the Boston accent, which should be constitutionally outlawed.)

Come to think of it, the Boston accent is probably the Cockney accent of the United States.