Many linguists attribute Minnesotans’ unusual single-tone pronunciation of long “a’s” and “o’s” to the influence of Scandinavian settlers, as those sounds are common in languages of that region.

But Minnesota’s large number of immigrants from Norway and Sweden didn’t arrive until the latter half of the 19th century, Haataja noted. The first Europeans to settle the area were largely English speakers from the British Isles. And both Scottish English and Irish English speakers are known for those same long “a” and “o” pronunciations.

Probably helped make it more distinct.