ZIP codes

ZIP codes in Rock County, Wisconsin

Rock County has 20 ZIP codes. 9 lie entirely inside it and 11 are shared with neighboring counties, so part of their land and their people are elsewhere. About 165,936 people live in the parts inside it (ACS 2020–2024).

By the All Map Tools Team

ZIP codes: 20; With 1% or more of their land inside
Entirely inside: 9; 99% or more of their land
Shared with other counties: 11; Most with Jefferson County (4)
Most populated ZIP: 53511; 48,701 people · Beloit
Least populated ZIP: 53501; 165 people
Largest ZIP by land: 53520; 120 sq mi · Brodhead

Map of the ZIP codes in Rock County

Entirely in the county (99% or more of its land)
Shared, mostly in this county
Shared, mostly in other counties
Neighboring counties

Open in the interactive tool

Each area is a ZIP code with its number where it fits. Hover over one to see its name.

All ZIP codes in Rock County

20 ZIP codes in Rock County, WI, by number
ZIP code	Main city	Population	Land in the county	Residents in the county
53114	Darien	1,979	24%	≈ 341
53190	Whitewater	20,499	27%	≈ 934
53501	—	165	100%	165
53502	Albany	2,393	1.5%	≈ 31
53505	—	358	100%	358
53511	Beloit	48,701	100%	48,701
53520	Brodhead	6,687	53%	≈ 1,982
53521	Brooklyn	3,640	8.5%	≈ 626
53525	Clinton	4,066	95%	≈ 3,879
53534	Edgerton	12,241	52%	≈ 10,202
53536	Evansville	9,547	100%	9,547
53537	Footville	752	100%	752
53538	Lake Koshkonong	18,813	1.7%	≈ 297
53545	Janesville	24,703	100%	24,703
53546	Janesville	29,867	100%	29,867
53548	Janesville	19,916	100%	19,916
53563	Milton	11,280	98%	≈ 11,225
53576	Orfordville	2,131	100%	2,131
53585	Sharon	2,264	4.6%	≈ 107
53589	Stoughton	19,550	2.1%	≈ 172

ZIP codes shared with other counties

These 11 ZIP codes have part of their land in another county. The first figure is the share of their land in Rock County; then, where the rest lies.

53114 (Darien): 24% here; 76% in Walworth County.
53190 (Whitewater): 27% here; 49% in Walworth County and 24% in Jefferson County.
53502 (Albany): 1.5% here; 98% in Green County.
53520 (Brodhead): 53% here; 47% in Green County.
53521 (Brooklyn): 8.5% here; 50% in Green County and 41% in Dane County.
53525 (Clinton): 95% here; 5.4% in Walworth County.
53534 (Edgerton): 52% here; 43% in Dane County and 4.9% in Jefferson County.
53538 (Lake Koshkonong): 1.7% here; 98% in Jefferson County.
53563 (Milton): 98% here; 1.6% in Jefferson County.
53585 (Sharon): 4.6% here; 95% in Walworth County.
53589 (Stoughton): 2.1% here; 98% in Dane County.

Cities and prefixes

By main city (the city, town or CDP each ZIP shares the most land with), the ones with the most are Janesville (3), Albany (1), Beloit (1), Brodhead (1), Brooklyn (1), and Clinton (1); 16 places in all.

They start with 2 different three-digit prefixes, one per USPS sorting center: 531 and 535.

Neighboring counties

Each one with its ZIP codes. Those without a page of their own open in the tool.

Tools for this county

ZIP codes by county or city The same ZIP codes on an interactive map, with the list as CSV or to copy County map with cities Its cities, towns and CDPs with their population ZIP codes in a radius The ZIP codes within 10 miles of its center, or any distance you like

Sources

U.S. Census Bureau, 2020 ZCTA to County, ZCTA to Place and ZCTA to Census Tract Relationship Files (and the 2022 County Subdivision to ZCTA file for Connecticut). Public domain.
U.S. Census Bureau, American Community Survey 2020–2024 5-year estimates, table B01003 (population of each ZIP code, census tract and Connecticut town). Public domain.
U.S. Census Bureau, Vintage 2025 Population Estimates (county population) and 2025 Gazetteer Files (land area and interior point of each ZIP code). Public domain.
U.S. Census Bureau, Cartographic Boundary Files: ZCTAs 2020 and counties 2025, 1:500,000; county adjacency file 2025. Public domain.

How we count. ZIP codes here are the Census Bureau’s ZIP Code Tabulation Areas (ZCTAs), the areas it draws to match USPS ZIP codes; ZIPs with no area of their own (PO boxes, single buildings) aren’t included. A ZIP can cross county lines: “Land in the county” is the exact share of its land inside, from the Census relationship files. “Residents in the county” is the whole ZIP for those entirely inside; for shared ones it’s an estimate, spreading the people of each census tract over the land it shares with the ZIP. Population: ACS 2020–2024. Methodology.

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