Zip Code 54421 — Colby, WI
54421 is a ZIP Code associated with Colby, WI, located within Marathon. The postal region supports an estimated population of 3,468 residents across Data Pending housing units, with a population density of 19.2 people per square mile.
WorldPlaceData database updated: October 2026
📍 View location on OpenStreetMap (44.898660, -90.295320)
| Data Metric | Local Statistic |
|---|
| Postal / Zip Code | 54421 |
| Primary City | Colby |
| State / Province | WI |
| County | Marathon |
| Total Population | 3,468 |
| Median Household Income | Data Pending |
| Total Housing Units | Data Pending |
| Population Density | 19.2 people/sq mi |
| Timezone | America/Chicago |
How 54421 Compares
| Metric | ZIP 54421 | Marathon County | WI State Average |
|---|
| Population | 3,468 | 131,688 | 5,914,913 |
| Median Income | Data Pending | N/A | N/A |
| Population Density | 19.2 /sq mi | -- | -- |
Nearby ZIP Codes
Data Sources & Methodology: Geographic coordinates and ZIP Code assignments are derived from underlying geographic and postal datasets. Note that ZIP Codes are USPS postal delivery areas, while Census ZCTAs are statistical approximation areas. Read full methodology →