Michigan · Eastern Time
231 Area Code
Area code 231 is in Michigan, serving western and northern Lower Michigan, including Muskegon and Traverse City. It is in the Eastern Time zone.
Last updated October 1, 2026 · Source: NANPA
Where is the 231 area code?
231 is a Michigan area code covering western and northern Lower Michigan, including Muskegon and Traverse City. In the wider directory it sits in the Midwest region.
Cities in the 231 area code
- Muskegon
- Traverse City
- Norton Shores
- Petoskey
- Cadillac
- Ludington
- Big Rapids
- Manistee
- Fremont
- Charlevoix
- Cheboygan
Counties served by 231
Muskegon County, Grand Traverse County, Emmet County, Wexford County, Mason County, Mecosta County, Manistee County, Newaygo County, Charlevoix County and Oceana County.
Time zone note: Eastern statewide except four Upper Peninsula counties near Wisconsin (Central).
Dialing 231
Muskegon, MI is currently served by the single area code 231, with no overlay. Ten-digit dialing (area code + seven-digit number) always works and is increasingly the norm nationwide; some local calls may still connect with seven digits. If a future overlay is added, 10-digit dialing would become mandatory.
From outside the US, dial +1 231 followed by the seven-digit number.
History of the 231 area code
231 went into service on June 5, 1999, created when it was split from 616. It serves Muskegon and the surrounding part of Michigan. For how codes are created, split, and overlaid, see how area codes work.
Is 231 a scam or spam risk?
231 is a legitimate geographic area code, not a premium or toll line, so a call from it costs you nothing extra. That said, scammers frequently spoof real local area codes to look familiar on caller ID. A genuine 231 number on your screen is no guarantee the caller is in Muskegon, MI or trustworthy. See spam & scam-risk area codes for how spoofing works and how to respond.
Other Michigan area codes
Explore more
See every code in Michigan, compare codes across the Midwest region, or view all Eastern Time codes. You can also browse the 2XX block or the complete numeric list of US area codes.
New to how this all works? Start with how area codes work, then read up on overlays, 10-digit dialing, and spam & scam-risk codes. To check another number, use the area code lookup tool.
Quick answers
231 area code FAQ
Where is the 231 area code?
The 231 area code is in Michigan, covering western and northern Lower Michigan, including Muskegon and Traverse City, in the Midwest region.
What cities are in the 231 area code?
Cities in the 231 area code include Muskegon, Traverse City, Norton Shores, Petoskey, Cadillac, Ludington, Big Rapids, Manistee, Fremont and Charlevoix.
What time zone is 231 in?
231 is in the Eastern Time zone. Eastern statewide except four Upper Peninsula counties near Wisconsin (Central).
When did the 231 area code start?
231 went into service on June 5, 1999.
Do I have to dial 10 digits for 231?
Ten-digit dialing always works, and many areas now require it; some local calls in this area may still connect with seven digits.
Is 231 a toll-free or premium code?
No. 231 is a standard geographic area code, so calling it costs the same as any local or long-distance call on your plan. Toll-free calls use 800, 888, 877, 866, 855, 844 or 833.