| ZIP Codes: | 10 ZIP Codes (10 Standard, 0 PO Box, 0 Unique) [See All] |
| Area Codes: | 262 / 274 / 920 |
| Timezone: | Central (GMT -06:00) |
| Local Time: | 2:14:19 PM |
| Population: | 76,915 [See All] |
| FIPS: | 55055 |
| CBSA: | Watertown-Fort Atkinson, WI |
| Land Area: | 534 sq mi |
| Water Area: | 26 sq mi |
| Coordinates: | 43.0498, -88.7423 |
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76,915 residents live across 10 ZIPs covering 534 sq mi, served by 10 distinct USPS-recognized cities.
Population moved from 75,932 to 76,915 from 2014 to 2024 — a +1.3% change. 6 ZIPs gained residents, 4 lost.
The county's wealthiest ZIP 53137 (Helenville, $116,550 median) and poorest ZIP 53094 (Watertown, $73,443) are 6.8 miles apart — a 1.6× income gap across local geography.
Median home values vary 1.6× across this county — from $237,500 in 53094 (Watertown) to $371,500 in 53178 (Sullivan).
Density varies 4× across the county — from 53 people/sq mi in 53137 (Helenville) to 222 in 53551 (Lake Mills).
Educational attainment ranges from 21.8% bachelor's+ in 53094 (Watertown) to 45.3% in 53551 (Lake Mills) — the breadth of educational profiles across the area.
Within Wisconsin, this is the #22 most populous of 73 counties and ranks #6 for median household income .
Weighted by population, the typical household earns about $84,695 across the county — reflecting what a typical resident sees, not a simple ZIP average.
27.7% of adults age 25+ hold a bachelor's degree or higher (15,182 of 54,894 reporting).
10 Standard delivery, 0 PO Box only, 0 single-entity Unique ZIPs serve this county.
| ZIP | City | Type | Population | Median Income | Area (sq mi) | 10-yr Growth |
|---|---|---|---|---|---|---|
| 53538 | Fort Atkinson | Standard | 18,813 | $82,783 | 102.3 | 1.2% |
| 53094 | Watertown | Standard | 17,998 | $73,443 | 86.3 | -7.0% |
| 53549 | Jefferson | Standard | 9,873 | $80,101 | 71.7 | -2.6% |
| 53551 | Lake Mills | Standard | 9,731 | $94,401 | 43.8 | 15.6% |
| 53594 | Waterloo | Standard | 5,199 | $88,390 | 71.0 | 2.0% |
| 53038 | Johnson Creek | Standard | 4,192 | $96,127 | 31.6 | 2.7% |
| 53036 | Ixonia | Standard | 3,730 | $92,674 | 33.6 | 40.2% |
| 53156 | Palmyra | Standard | 3,232 | $85,313 | 32.6 | 5.5% |
| 53178 | Sullivan | Standard | 2,497 | $99,875 | 29.7 | -5.8% |
| 53137 | Helenville | Standard | 1,650 | $116,550 | 31.2 | -12.1% |