406 Area Code: Billings, Montana

Montana is served by a single area code, 406, which covers the entire state. Billings, in the Yellowstone River valley, anchors the directory's records here. The city sits at the foot of a band of sandstone rims that rise abruptly above the river plain — the Rims define much of the city's visual character — and Billings has long functioned as the regional commercial center for a substantial slice of the northern Rockies and the surrounding plains. The local working economy reflects healthcare, oil-and-gas activity in the surrounding Williston Basin, agricultural processing, and a steady role as the regional retail center. The 406 footprint takes in Missoula, Bozeman, Great Falls, Helena, and the rest of the state's communities.

Because 406 covers Montana entirely, the directory's records associated with 406 numbers do not surface a recurring set of out-of-state cities through the routine cross-linkage patterns that dominate larger codes. Where other-place names do appear, they reflect the same kinds of public-record dynamics seen elsewhere — numbers porting between carriers, addresses tied to multiple residences, and prior registrations surfacing alongside current ones. The directory currently documents 461 distinct prefixes within 406 in detail, a working subset of the prefix population the code actually carries.

Billings's home values come in close to the US median, with median household income running below the national figure but not severely so. The city's median age sits close to the US reading, and population places Billings as the largest city in Montana — substantial in its regional context, but small in the broader US context.