231 Area Code: Muskegon, Michigan

Western and northwestern Michigan is served by the 231 area code, with Muskegon as the primary city in the directory's records. Muskegon sits along Lake Michigan at the mouth of the Muskegon River, on a stretch of the lakeshore that supported a major lumbering industry in the late nineteenth century — the city was one of the largest sawmill centers in the world before the white pine forests gave out — and a substantial industrial base built up after that. The 231 footprint reaches through Traverse City, Cadillac, Manistee, and the surrounding lakeshore and inland counties of northwestern Michigan.

Records linked to 231 numbers in the directory often include other Michigan cities — Ann Arbor, Detroit, Flint, and Grand Rapids among them. None of those are inside the 231 footprint. The pattern reflects standard public-record dynamics, with phone numbers porting across Michigan and addresses linked across multiple cities. The directory currently documents 324 distinct prefixes within 231 in detail, a working subset of the prefix population the code carries.

Muskegon's home values come in well below the US median, in line with broader western Michigan pricing. Median household income runs notably below the national figure, the city's median age sits a couple of years under the US reading, and population is modest in absolute terms — the city itself is small, but the broader 231 footprint covers a substantial geographic stretch of Michigan's western Lower Peninsula, including the resort communities of Traverse City and the Sleeping Bear Dunes National Lakeshore region.