What is a question about this article? If the question is unanswerable, say "unanswerable".

I-275 runs north–south from I-75 in the south to the junction of I-96 and I-696 in the north, providing a bypass through the western suburbs of Detroit. I-375 is a short spur route in downtown Detroit, an extension of the Chrysler Freeway. I-696 (Reuther Freeway) runs east–west from the junction of I-96 and I-275, providing a route through the northern suburbs of Detroit. Taken together, I-275 and I-696 form a semicircle around Detroit. Michigan state highways designated with the letter M serve to connect major freeways.

Michigan uses what letter to designate roads that connect major highways?
M