Census tract · Rock County
Census Tract 4, Rock County, Wisconsin
Census Tract 4, GEOID 55105000400, in Rock County, Wisconsin, entirely within Janesville. 3,936 residents in the ACS 2020-2024 5-year estimates (±935); the 2020 Census counted 3,700.
Residents, 2020-2024
3,936
±935 (90% margin)
2020 Census count: 3,700
Median household income
$65,876
±$15,253 (90% margin)
Rock County: $75,673
Median home value
$194,400
±$30,414 (90% margin)
Rock County: $231,600
Median gross rent
$953
±$135 (90% margin)
Rock County: $1,037
Where is Census Tract 4?
Census Tract 4 is one of 41 census tracts in Rock County, Wisconsin. It covers 1.35 square miles of land, 2,745 residents per square mile in 2020. Its GEOID, 55105000400, names it uniquely (how tract numbers and GEOIDs work).
| Place | Share of the tract |
|---|---|
| Janesville | 100% |
6 census tracts border Census Tract 4: Tract 1 ($22,204), Tract 3 ($49,288), Tract 5 ($73,311), Tract 6 ($66,444), Tract 11 ($66,600) and Tract 12.01 ($90,597). The figure in brackets is each tract's median household income.
Whether a tract counts as low- or moderate-income for bank lending (the Community Reinvestment Act) is set by the FFIEC against its metro area's family income: look it up in the FFIEC census geocoder.
Source: 2024 Gazetteer and 2020 block assignment files, U.S. Census Bureau · Census reference files
How many people live in Census Tract 4?
The 2020-2024 American Community Survey puts Census Tract 4's population at 3,936 (±935) in 1,598 households; the 2020 Census counted 3,700 residents and 1,615 housing units.
| Measure | Tract 4 | Janesville |
|---|---|---|
| Total population | 3,936 ±935 | 66,030 |
| Households | 1,598 ±253 | 28,326 |
| Average household size | 2.45 ±0.33 | 2.30 |
| Housing units | 1,788 ±235 | 29,330 |
Source: American Community Survey 2020-2024 5-year estimates, U.S. Census Bureau (released January 2026); 2020 Census P.L. 94-171 · Check it at data.census.gov
Who lives in Census Tract 4?
The median resident of Census Tract 4 is 38.4 years old; 26.7% are under 18 and 11.2% are 65 or older. The largest group is non-Hispanic white residents at 83.3%, then Hispanic or Latino residents (of any race) at 12.1%.
| Measure | Tract 4 | Janesville |
|---|---|---|
| Median age | 38.4 ±6.2 | 40.7 |
| Under 18 years | 26.7% ±7.2 pts | 21.2% |
| 65 years and over | 11.2% ±4.2 pts | 18.2% |
| Hispanic or Latino (any race) | 12.1% ±10.1 pts | 7.8% |
| White alone, not Hispanic | 83.3% ±10.4 pts | 83.8% |
| Black or African American alone, not Hispanic | 2.7% ±2.2 pts | 3.0% |
| Asian alone, not Hispanic | 0.0% ±0.6 pts | 1.6% |
| American Indian and Alaska Native alone, not Hispanic | 0.0% ±0.6 pts | 0.1% |
| Native Hawaiian and Other Pacific Islander alone, not Hispanic | 0.2% ±0.4 pts | 0.0% |
| Two or more races, not Hispanic | 1.6% ±1.5 pts | 3.5% |
| Some other race alone, not Hispanic | 0.0% ±0.6 pts | 0.3% |
| Born outside the United States | 4.4% ±4.9 pts | 3.8% |
| Speak a language other than English at home (age 5+) | 8.2% ±8.6 pts | 7.5% |
| Civilian veterans (age 18+) | 4.3% ±2.7 pts | 6.7% |
| With a disability | 12.9% ±5.1 pts | 13.0% |
| No health insurance coverage | 13.9% ±7.6 pts | 5.6% |
| High school graduate or higher (age 25+) | 92.1% ±5.8 pts | 94.4% |
| Bachelor's degree or higher (age 25+) | 25.2% ±12.8 pts | 27.3% |
| Graduate or professional degree (age 25+) | 6.4% ±4.8 pts | 8.5% |
| Lived in the same house a year earlier | 92.3% ±6.4 pts | 90.7% |
Source: American Community Survey 2020-2024 5-year estimates, U.S. Census Bureau (released January 2026) (Data Profiles DP02, DP05) · Check it at data.census.gov
What do households in Census Tract 4 earn?
Half of the 1,598 households in Census Tract 4 earn less than $65,876 a year (±$15,253), against $75,673 across Rock County: 28th highest of the county's 41 tracts with a reliable estimate. 13.8% of residents live below the poverty line.
| Measure | Tract 4 | Janesville |
|---|---|---|
| Median household income | $65,876 ±$15,253 | $73,446 |
| Mean household income | $76,193 ±$8,768 | $85,681 |
| Per capita income | $31,951 ±$3,263 | $37,762 |
| People below the poverty line | 13.8% ±6.4 pts | 9.0% |
| Children under 18 below the poverty line | 21.0% ±15.6 pts | 11.7% |
| Households receiving SNAP | 17.4% ±7.1 pts | 12.8% |
| Households with a computer | 88.2% ±6.9 pts | 96.5% |
| Households with a broadband subscription | 87.4% ±6.9 pts | 91.3% |
Source: American Community Survey 2020-2024 5-year estimates, U.S. Census Bureau (released January 2026) (Data Profile DP03) · Check it at data.census.gov
What does housing cost in Census Tract 4?
Owners occupy 61.9% of Census Tract 4's occupied homes and renters 38.1%. The median owner-occupied home is valued at $194,400 by its owner (±$30,414). The median renter pays $953 a month including utilities, and 31.5% of renters pay 35% or more of their income on rent.
| Measure | Tract 4 | Janesville |
|---|---|---|
| Median home value (owner-occupied) | $194,400 ±$30,414 | $223,400 |
| Median gross rent | $953 ±$135 | $1,054 |
| Renters paying 35% or more of income on rent | 31.5% ±15.3 pts | 34.4% |
| Median monthly owner costs, with a mortgage | $1,392 ±$90 | $1,510 |
| Owner-occupied homes | 61.9% ±10.0 pts | 67.3% |
| Renter-occupied homes | 38.1% ±10.0 pts | 32.7% |
| Housing units | 1,788 ±235 | 29,330 |
| Single-family detached homes | 71.6% ±9.3 pts | 67.8% |
| Mobile homes | 5.5% ±5.9 pts | 2.1% |
| Built 2020 or later | 0.0% ±1.2 pts | 1.3% |
| Built 2010 to 2019 | 5.9% ±4.9 pts | 3.8% |
| Built 1939 or earlier | 38.5% ±8.5 pts | 14.2% |
| Households with no vehicle | 12.7% ±7.0 pts | 5.9% |
Source: American Community Survey 2020-2024 5-year estimates, U.S. Census Bureau (released January 2026) (Data Profile DP04) · Check it at data.census.gov
How do people in Census Tract 4 get to work?
72.0% of Census Tract 4's workers drive alone and 13.6% work from home. The average trip to work takes 20.5 minutes.
| Measure | Tract 4 | Janesville |
|---|---|---|
| In the labor force (age 16+) | 72.7% ±7.3 pts | 65.5% |
| Unemployment rate | 3.4% ±2.7 pts | 4.1% |
| Drove alone to work | 72.0% ±8.7 pts | 80.0% |
| Carpooled | 6.2% ±4.6 pts | 7.3% |
| Public transportation | 2.6% ±2.4 pts | 0.6% |
| Walked | 2.0% ±2.2 pts | 1.4% |
| Worked from home | 13.6% ±7.8 pts | 9.5% |
| Mean travel time to work | 20.5 min ±3.5 | 21.9 min |
Source: American Community Survey 2020-2024 5-year estimates, U.S. Census Bureau (released January 2026) (Data Profile DP03) · Check it at data.census.gov
How does Census Tract 4 compare with the other tracts in Rock County?
Among Rock County's tracts with a reliable estimate, Census Tract 4 ranks as shown below (1 = highest).
| Measure | In Rock County | In Janesville |
|---|---|---|
| Population | 21st of 41 | 11th of 18 |
| Residents per square mile | 16th of 41 | 9th of 18 |
| Median household income | 28th of 41 | 12th of 18 |
| Per capita income | 32nd of 41 | 15th of 18 |
| Median home value | 26th of 41 | 12th of 18 |
| Median gross rent | 29th of 41 | 14th of 18 |
| Poverty rate | 10th of 35 | 5th of 16 |
| Bachelor's degree or higher | 23rd of 39 | 11th of 17 |
| Median age | 29th of 41 | 14th of 18 |
| Owner-occupied share | 30th of 41 | 12th of 18 |
The tracts next to it on Rock County's income ladder
| Tract | Rank | Median household income |
|---|---|---|
| Tract 30.01 | 25th | $71,193±$8,140 · within the margin of this tract |
| Tract 11 | 26th | $66,600±$17,502 · within the margin of this tract |
| Tract 6 | 27th | $66,444±$10,823 · within the margin of this tract |
| Tract 4 | 28th | $65,876±$15,253 |
| Tract 21 | 29th | $63,507±$7,409 · within the margin of this tract |
| Tract 2 | 30th | $63,194±$27,163 · within the margin of this tract |
| Tract 7 | 31st | $62,436±$11,502 · within the margin of this tract |
"Within the margin": the two incomes differ by less than their combined 90% margins, so the survey cannot say which is higher and the ranks between them are not firm.
Source: PlainCities ranks computed from the American Community Survey 2020-2024 5-year estimates, U.S. Census Bureau (released January 2026) · How ranks are computed
How reliable are the figures for Census Tract 4?
3 of the 18 figures for Census Tract 4 on this page carry a coefficient of variation over 40% and are marked with a ring: they come from a small sample, so read them as rough.
A census tract's figures rest on a few hundred sampled households over five years, so its margins are wider than a city's. Two tracts differ only when the gap between them is larger than their combined 90% margin (the square root of the sum of the two squared margins). How to read a margin of error.
Source: American Community Survey 2020-2024 5-year estimates, U.S. Census Bureau (released January 2026): margins of error as published · Check it at data.census.gov
How these figures are made: methodology and release checks · reading a margin of error · every state · corrections