231 Area Code — Michigan
231 is a North American Numbering Plan area code for Michigan, the United States. It covers about 701,161 people in 133 towns and 142 ZIP codes, including Muskegon, Traverse City and Cadillac.
| Field | Value |
|---|---|
| Area code | 231 |
| Country | United States (+1) |
| State / province | Michigan |
| Type | Standalone (no other NANP code covers the same towns) |
| Time zone | Eastern |
| Population covered | 701,161 |
| Towns covered | 133 |
| ZIP codes | 142 |
| Approx. centre | 44.397, -85.598 |
Where area code 231 is used
Area code 231 is assigned to Michigan, the United States, inside the North American Numbering Plan. Numbers in the code are written (231) NXX-XXXX at home and +1 231 NXX-XXXX when dialled from outside Canada and the United States. Since the NANP moved to 10-digit dialling you must always include the area code, even for a local call.
Towns and cities in area code 231
The 133 towns below are the largest in the 231 footprint, ranked by population. Every one of them links to its own page with the full list of area codes and ZIP codes for that town.
| Town | County | Population | ZIP codes |
|---|---|---|---|
| Muskegon | Muskegon County | 130,770 | 6 |
| Traverse City | Grand Traverse County | 78,862 | 4 |
| Cadillac | Wexford County | 22,092 | 1 |
| Big Rapids | Mecosta County | 18,407 | 1 |
| Petoskey | Emmet County | 18,221 | 1 |
| Ludington | Mason County | 17,184 | 1 |
| Manistee | Manistee County | 14,578 | 1 |
| Cheboygan | Cheboygan County | 13,891 | 1 |
| Newaygo | Newaygo County | 13,149 | 1 |
| Fremont | Newaygo County | 12,097 | 2 |
| Twin Lake | Muskegon County | 11,086 | 1 |
| Whitehall | Muskegon County | 9,707 | 1 |
Counties covered
| County | ZIP codes |
|---|---|
| Muskegon County | 13 |
| Emmet County | 12 |
| Antrim County | 11 |
| Grand Traverse County | 10 |
| Manistee County | 10 |
| Leelanau County | 9 |
| Newaygo County | 8 |
| Oceana County | 8 |
| Benzie County | 8 |
| Osceola County | 7 |
| Lake County | 6 |
| Mecosta County | 6 |
Nearby area codes
How to dial area code 231
- Within North America: 231 + 7-digit number (231-NXX-XXXX). The leading 1 is optional on a mobile phone and required on most landlines for long-distance.
- From abroad: your country's international prefix, then 1, then 231, then the 7-digit number — for example 00 1 231 NXX-XXXX from most of Europe.
Frequently asked questions
What area code is 231?
231 is a North American Numbering Plan area code assigned to Michigan, the United States. It covers about 701,161 people in 133 towns.
Is 231 a US or Canadian area code?
231 is a United States area code. Canada and the United States share the +1 country code, so both are part of the same numbering plan.
What time zone is area code 231 in?
Area code 231 is in the Eastern time zone.
Do I have to dial 10 digits?
Yes. Every NANP call now requires the area code plus the seven-digit number, even for a local call.