ZIP 83657 falls in Gem County, Idaho, where we hold 3,232 parcels measured as septic county-wide and 3,255 on sewer. We do not have a per-ZIP parcel count for this county, so this is the county total, not a count specific to ZIP 83657.
ZCTA 83657 is not entirely inside one county. Land-area share is from the 2020 Census ZCTA-to-county relationship file.
| County | Land in this ZIP | Documents held | On septic (county) | On sewer (county) |
|---|---|---|---|---|
| Gem County, Idaho | 98% | 6,397 | 3,232 | 3,255 |
| Valley County, Idaho | 2% | 7,967 | 4,534 | 6,548 |
Land-area overlap is from the 2020 Census Bureau ZCTA5-to-county relationship file, not an estimate of ours. Parcel and document counts are rows we hold, not a survey of every property in the ZIP. Last verified 2026-09-01.
We hold 3,232 parcels measured as septic for Gem County, Idaho as a whole, not broken out by ZIP.
ZIP 83657 spans 2 counties: Gem County, Idaho, Valley County, Idaho.