Rock County GIS Maps
Rock County, Wisconsin, has 163,687 residents across 73,139 parcels and covers 718.1 square miles. The population grew 2.1% between the 2010 and 2020 census. More residents moved in than left over that decade. The FIPS code for Rock County is 55105.
Janesville is the county's largest population center. Rock County also includes 13 zip codes, 14 public school districts and 51 municipalities. Those boundaries help explain why population, schools, and housing can look different from one part of the county to another. The map below shows how those county lines, zip codes, and school districts fit together, and the sections that follow use that same geography to show parcel data, population, demographics, school enrollment and housing patterns in more detail.
Maps, GIS layers, Parcels and sample data. Paid packages add full layers, analytics and database files.
Rock County Trends
- Population
- 163,687▴
- Median Home Value
- $215,900▴
- K-12 Enrollment
- 34,653▾
County analytics dashboards with historical trends & projections included in package downloads.
Free starter access previews county maps, lightweight GIS, and sample data. Paid packages unlock full GIS layers, analytics, and database files.
Rock County Maps
The maps below show a few of the county map styles included in our downloads. County packages include map exports in JPEG, PNG, SVG, PDF and GeoTIFF formats plus more than 20 GIS layers for mapping, research and analysis. Available layers include zip codes, area codes, subdivisions, school districts, political boundaries, roads, water features, points of interest and more.
County packages also include historical county demographics, business intelligence, analytical dashboards, AI-ready prompts, markdown files and related reference data. Everything is organized to save hours of manual work collecting current data, cleaning it and joining it together. That makes it easier to move faster on analytics, due diligence, business planning and location research. Paid packages are built for commercial use, but some package contents include source-specific attribution or notice guidance. Review Licensing & Data Source Notices.
Rock County Parcels
Rock County has 73,139 mapped parcels covering 456,052 acres. The median assessed value is $205,100. The median lot size is 0.31 acres. 7,519 parcels are 10 acres or larger. The records carry 55,697 distinct owner names. Owner names, mailing addresses and lot sizes are on nearly every parcel. Site addresses reach 88.7%. Assessed values reach 95.8%. Browse the interactive Rock County Parcel viewer here.
Rock County Parcel Data Coverage
| Field | Parcels | Coverage |
|---|---|---|
| Parcel ID | 73,139 | 100% |
| Owner name | 73,127 | 99.9% |
| Owner mailing address | 73,127 | 99.9% |
| Site address | 64,867 | 88.7% |
| Land use code | 70,068 | 95.8% |
| Land use description | 0 | 0% |
| Assessed value | 70,067 | 95.8% |
| Land value | 70,066 | 95.8% |
| Improvement value | 70,067 | 95.8% |
| Acreage | 72,074 | 98.5% |
| Parcel boundary | 73,139 | 100% |
| Download all Rock County parcels. | ||
Field coverage measured across all Rock County parcel records.
Rock County Population
Rock County had 163,687 residents in 2020. That was 2.1% higher than in 2010. Rock County added 11,380 people between 2000 and 2020, which points to steady long-term growth. The county is fairly spread out, with about 228 people per square mile. Some of the county's most populated postal areas include Beloit, Janesville and Janesville.
Population Trend in Rock County WI
Rock County Population per 2000, 2010 and 2020 census counts with a baseline 2030 projection.
Rock County Zip Codes
Rock County has 13 zip codes. Some of the county's most populated zip codes include Beloit (53511), Janesville (53546) and Janesville (53545). Beloit is the largest zip by population, with about 48,659 residents or 30% of the county total. Together, the three largest zips account for about 63% of all county residents based on 2020 population estimates.
Most Populated Zip Codes in Rock County WI
| ZIP | Area | Population | Trend |
|---|---|---|---|
| 53511 | Beloit | 48,659 | ▾ -0.6% |
| 53546 | Janesville | 31,190 | ▴ 1.8% |
| 53545 | Janesville | 23,318 | ▴ 0.9% |
| 53548 | Janesville | 19,233 | ▴ 3.6% |
| 53534 | Edgerton | 12,752 | ▴ 10.8% |
| Download all zip code data | |||
Rock County Zip Code populations and trends per most recent census data.
Rock County Demographics
Rock County has a median age of 40.1, which is close to the Wisconsin average. About 22.7% of residents are under 18, while 17.3% are 65 or older. That gives the county a fairly even mix of younger families and older adults. The largest age group is 25 to 44 at about 30.9% of the population, which points to a solid working-age base. About 25.7% of adults have a bachelor's degree or higher, above the statewide figure of 32.8%. The county is majority White by population, with Hispanic, Asian, Black and multiracial residents making up a meaningful share of the local mix.
Key Demographics for Rock County WI
Median Age
40.1
Under 18
22.7%
Age 65+
17.3%
Bachelor's+
25.7%
Rock County School Districts
Rock County is served by 14 public school districts with 34,653 students enrolled in 2024. The largest districts on the county map are Janesville, Beloit and Milton. Those three districts account for about 51% of public school enrollment in the map area. Total enrollment has stayed fairly steady in recent years, but it is slightly lower than it was in 2017.
Largest School Districts by Enrollment in Rock County WI
| District | Enrollment | Share | Trend |
|---|---|---|---|
| Janesville School District | 9,355 | 27% | ▾ -0.6% |
| Beloit School District | 4,958 | 14.3% | ▾ -2.7% |
| Milton School District | 3,461 | 10% | ▴ 0.3% |
| Stoughton Area School District | 2,735 | 7.9% | ▾ -1.2% |
| Fort Atkinson School District | 2,263 | 6.5% | ▾ -3% |
| Download all school district data | |||
Rock County school district enrollment and trends per most recent NCES reporting data.
Rock County Housing & Real Estate
Rock County has a median home value of $215,900 and a median gross rent of $1,019. About 71% of occupied homes in the county are owner-occupied, so the local housing market leans heavily toward ownership. Home values run below the Wisconsin median, while rents come in below the state average. In March 2026, the median listing price was $354,671 and homes spent about 45 days on the market.
Rock County Housing Mix
Rock County housing mix: owner, renter and vacant units.
Rock County Housing Trends
Rock County median home value and rent trend (last 5 years).
Businesses in Rock County, WI
Rock County has 6,477 business listings across 743 categories. The largest categories in Rock County business listings are Churches & Religious Organizations (165, 2.5%), Parks & Recreation (134, 2.1%), and Beauty Salons (120, 1.9%). The full Rock County business listings dataset includes names, categories, addresses and contact details where available. Rock County packages also include U.S. Census County Business Patterns data with establishment counts, employment and payroll by industry sector.
Top Business Categories in Rock County, WI
| Category | Businesses | Share |
|---|---|---|
| Churches & Religious Organizations | 165 | 2.5% |
| Parks & Recreation | 134 | 2.1% |
| Beauty Salons | 120 | 1.9% |
| Auto Repair | 110 | 1.7% |
| Contractors | 109 | 1.7% |
| Professional Services | 81 | 1.3% |
| Community & Nonprofits | 78 | 1.2% |
| Real Estate Agents | 78 | 1.2% |
| Gas Stations | 78 | 1.2% |
| Landmark And Historical Building | 68 | 1.0% |
Rock County Business Listings
| Business | Category | City |
|---|---|---|
| Alden Meadow Park Rehabilitation & Health Care Center | Abuse And Addiction Treatment | Clinton |
| Bothunshire | Accommodation | Janesville |
| Personalized Accounting LLC | Accountant | Beloit |
| Hope For All Community Center | Active Life | Beloit |
| Allison Becker, ND, LAc | Acupuncture | Evansville |
| Adoption Avenues | Adoption Services | Janesville |
| Blu Astor Cabaret | Adult Entertainment | Janesville |
| GetSpecific Website Marketing | Advertising Agency | Edgerton |
| Up With Dance | Aerial Fitness Center | Janesville |
| CCI Limestone Quarry | Aggregate Supplier | Beloit |
| Download Rock County business listings | ||
Rock County business listings sourced from Overture Maps. Includes locations with a high level of confidence.
Rock County Basemaps
Rock County map and data packages include a set of useful basemaps to help you get started quickly. These include a custom light grey canvas, USGS topo, imagery and other reference layers that make it easier to build clear, meaningful county maps using the included GIS layers, your own data or both. Pre-rendered map tiles for the light grey basemap are included so you can use them offline or host them on your own CDN.
Get the Full Rock County Data Package
This page shows a preview of what's included in the Rock County data package. The full package gives you a ready-to-use county data system with GIS layers, historical data, maps, database files and planning tools that save hours of manual data gathering, cleanup and joins. Everything is organized to help you skip data wrangling and start analysis faster.
- 20+ GIS layers for parcels, zip codes, school districts, roads, water, boundaries and more
- Historical county demographics, housing, income and trend data
- ZIP code population files and school district enrollment history
- Database files, markdowns, AI-ready prompts and documentation
- Map exports in PNG, JPEG, PDF, SVG and GeoTIFF formats
- Offline-ready data explorer, map and analytics tools
Paid packages support commercial use, client work, and derived outputs. Some package contents may include source-specific attribution or provider notices. See Licensing & Data Source Notices.
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Nearby Counties
Browse county data pages for the counties that border Rock County. These nearby pages include the same mix of county maps, demographic summaries, school district context, housing trends and package links.