Every area code in Montana

All Montana area codes, what each primarily serves, and which share ground with another.
Area code	Primarily serves	In service
406	Billings	1947

Which codes share the same ground

No Montana code shares its territory with another — each covers its own area, so an area code here still corresponds to a single part of the state.

Where Montana's communities sit

Each point is a Montana community, plotted from its record coordinates. The outline is the convex envelope of those points — a footprint, not a boundary.

Reference points and footprint
Not an official NANPA boundary
Not a USPS delivery area

Largest Montana cities and their codes

largest 25

Scope every area code assigned to Montana. Source LocalCallingGuide NPA list (2026-07 NPA list) and geoinfo-dataset (full_dataset) ZIP→NPA (2018 snapshot). Updated 16 July 2026. Overlay relationships come from the numbering-plan authority; the city match is computed.