They are really appealing to is Muslims of Middle Eastern descent, which would not include Black Muslims. Michigan would probably be the leading battleground state in terms of percentage of the population belonging to that demographic. There is no city in the country quite like Dearbornistan.
I think people would be quite surprised at where the concentrations of Muslims are in America. As you said, Dearborn is an odd place yet here 70 miles to the west I virtually never encounter any muslims aside from the black pseudo muslims.
Thee seems to be a heavy infestation in Minnesota and Nebraska. Even Texas is in the top ten in overall numbers but NY and California are the leaders.