That's cause you're just a chap, you see in the old days MISS was the abreviation and Mississippi boat registration us MI for the first part of the numbers. Then some yankee came along with a bright idea to shorten the abreviations to just 2 letters saving us an awesome .0357 seconds now when we right it, thanks yank, and apparently Mississippi had dibs on MI.
I do love when some guy from Illinois ask me, what part of Michigan you from, I just tell em about 30 miles south of Detroit!!!