I think this one is based on where people were born. If you want to actually picture a Mt Rushmore type image, consider Mississippi w/Elvis, BB King, Sam Cooke, and Muddy Waters...and that omits Howlin Wolf, Robert Johnson, Jimmie Rodgers, and Bo Diddley. Of course, nobody stays in MS, which is usually reduced to bragging, "We're #48" when they move up in various rankings.
For actual listening enjoyment, I could be happy with Minnesota's Dylan, Prince, Mould, and, Westerberg, especially if Dylan covers were included.