Take the 25-question test, with somewhat randomized questions, based on the Harvard Dialect Survey, and see your “heat map”.
My map centered in Iowa, with Minneapolis, Rockford, and Grand Rapids closest in language similarity. But I think I’ll need a translator the next time I go to Massachusetts.
(Some of the “correct” 😛 answers: Pop, garage sale, kitty-corner, there is a certain definition for freeway, aunt/ant identical. Those who grew up in Polk County will have to answer “other” for the question regarding Oct. 30. There’s no option for using water/drinking fountain interchangeably.)