On the shortlist of places and times in the United States I would not go to seek out authentic BBQ is 21st century Ann Arbor, Michigan. I can think of a few others:
San Francisco also 21st c. When it was grittier and realer in the Clint Eastwood as Harry Callahan days...maybe
Any of the major towns on the Maine downeast coast ever.
Amish country, Pennsylvania ever.
Waiting for contrary examples but...that was the top of my head list.