The upper peninsula ("U.P.") of Michigan is the place to get pasties in the United States. It's almost the only region of the United States that includes people who know how to pronounce "pasty."

http://kenanderson.net/pasties/michigan.html

http://www.upper-peninsula-now.com/pasties.html

http://www.exploringthenorth.com/foods/north.html

I've had a pasty in the U.P., and I'd be glad for pasties to become more generally available in the United States. As it is, my wife (who is Taiwanese) makes homemade meat pies, to surprisingly good effect from someone who didn't grow up eating them.