by Kristen Carney
Updated: June 20, 2024
The richest county in Illinois is Lake County with an average household income of $147,075 as of 2022 and 708,760 people as of 2023 according to the most current Census data available (citation).
Rank | County | Population | Average Income | Median Income |
---|---|---|---|---|
1 | Lake County | 708,760 | $147,075 | $104,553 |
2 | DuPage County | 921,213 | $144,731 | $107,035 |
3 | Will County | 700,728 | $126,188 | $103,678 |
4 | Kane County | 514,982 | $125,010 | $96,400 |
5 | McHenry County | 312,800 | $123,694 | $100,101 |
6 | Kendall County | 139,976 | $121,223 | $106,358 |
7 | Monroe County | 34,957 | $119,329 | $100,685 |
8 | Cook County | 5,087,072 | $113,411 | $78,304 |
9 | Grundy County | 53,578 | $107,987 | $89,993 |
10 | Calhoun County | 4,317 | $106,062 | $88,059 |
11 | Woodford County | 38,285 | $103,919 | $80,093 |
12 | Boone County | 53,202 | $100,719 | $80,502 |
13 | Piatt County | 16,714 | $100,385 | $81,151 |
14 | Clinton County | 36,785 | $99,933 | $78,054 |
15 | McLean County | 170,441 | $99,327 | $75,356 |
16 | Menard County | 11,954 | $99,217 | $84,846 |
17 | Jersey County | 21,091 | $97,649 | $77,607 |
18 | Sangamon County | 193,491 | $94,790 | $71,653 |
19 | Madison County | 262,752 | $93,528 | $71,759 |
20 | Effingham County | 34,331 | $93,523 | $73,181 |
We usually suggest using median income data – either instead of or in addition to – average income data as a true indicator of wealth. If you haven’t thought about median versus average since your last standardized test, you aren’t alone. Here’s what they are:
Now let’s say you had the following simplified set of income data.
Household 1: $30,000
Household 2: $50,000
Household 3: $1,000,000
The average income for this set is $360,000. The outlier data point ($1,000,000) skews the average WAY up. Conversely, the average income would be skewed WAY down if someone had an income of $500. The median income for the same data set is $50,000. Outlier data doesn’t skew the median.
So most business owners should use the median income as a true indicator of wealth, because it provides a more accurate representation of a typical income, especially in areas with significant income disparity.
If your target market is high-income households, the average income may be more relevant. This is because the average income can highlight the presence of a higher concentration of wealthy individuals, which is beneficial for luxury goods and services marketing. We’re using average income on this page because using the Census’s highest reported median value of $250,001 could result in multiple ties for the richest geography.
The Census' American Community Survey uses $250,000+ as a jam value for median income estimates to protect privacy, ensure data consistency, and simplify reporting. A "jam value" in survey data refers to a placeholder or default value used when actual data points are unavailable, incomplete, or exceed certain thresholds. We represent this jam value as $250,001 to make it easy for you to sort.
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United States Census Bureau. Annual Estimates of the Resident Population: April 1, 2020 to July 1, 2023. U.S. Census Bureau, Population Division. Web. May 2024. http://www.census.gov/.
United States Census Bureau. B01001 SEX BY AGE, 2022 American Community Survey 5-Year Estimates. U.S. Census Bureau, American Community Survey Office. Web. 7 December 2023. http://www.census.gov/.
United States Census Bureau. B19013 Median Household Income, 2022 American Community Survey 5-Year Estimates. U.S. Census Bureau, American Community Survey Office. Web. 7 December 2023. http://www.census.gov/.
United States Census Bureau. “DP03 SELECTED ECONOMIC CHARACTERISTICS.” 2022 American Community Survey 5-Year Estimates. U.S. Census Bureau, American Community Survey Office. Web. 07 December 2023. http://www.census.gov/.
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