Area code 231 - Wikipedia
Area code 231 was created in June 1999 by an area code split split of area code 616, which had served the entire western half of the Lower Peninsula, extending west from the north-south line aligned with the Mackinac Bridge. 231 was carved out of the northern part. It is centered around the western half of the territory generally defined as Northern Michigan. It also includes Muskegon, which is usually counted as part of West Michigan.
DA: 35 PA: 37 MOZ Rank: 56