Michigan currently utilizes 12 area codes. When first established by AT&T and the Bell System in 1947, 313 covered southeast Michigan including Detroit, 517 covered south-central portion of the lower peninsula of Michigan including Lansing, and 616 covered parts of Michigan including Grand Rapids, the upper peninsula, and the western portion of lower peninsula. The most recently added was 947 in 2002 as an overlay to 248. Today, 734 is the most populated with an estimated 1.4 million of the state's 9.9 million residents.
Sources: , telecom providers, and the .