by Kristen Carney
Updated: February 9, 2026
The richest county in Iowa is Dallas County with an average household income of $137,324 as of 2024 and 107,968 people as of 2024 according to the most current Census data available (citation).
| Rank | County | Population | Average Income | Median Income |
|---|---|---|---|---|
| 1 | Dallas County | 107,968 | $137,324 | $102,379 |
| 2 | Warren County | 54,409 | $111,331 | $94,588 |
| 3 | Mills County | 14,568 | $109,810 | $90,753 |
| 4 | Polk County | 503,175 | $109,398 | $83,576 |
| 5 | Johnson County | 156,639 | $108,874 | $74,935 |
| 6 | Bremer County | 25,204 | $108,261 | $86,784 |
| 7 | Madison County | 16,926 | $106,293 | $90,855 |
| 8 | Sioux County | 36,212 | $104,988 | $86,098 |
| 9 | Linn County | 230,004 | $104,478 | $77,649 |
| 10 | Scott County | 174,608 | $103,843 | $78,277 |
| 11 | Adams County | 3,622 | $103,589 | $71,875 |
| 12 | Dickinson County | 17,990 | $102,164 | $75,432 |
| 13 | Benton County | 25,724 | $101,158 | $86,962 |
| 14 | Plymouth County | 25,747 | $101,116 | $83,251 |
| 15 | Grundy County | 12,384 | $101,039 | $87,205 |
| 16 | Guthrie County | 10,688 | $100,744 | $77,711 |
| 17 | Marion County | 33,642 | $100,547 | $78,680 |
| 18 | Winneshiek County | 19,873 | $100,242 | $79,066 |
| 19 | Dubuque County | 99,030 | $100,177 | $77,630 |
| 20 | Boone County | 26,668 | $99,765 | $83,531 |
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.
Join thousands of subscribers and receive just 1 (ONE!) email a year in December when the US Census Bureau releases new income data for Iowa richest counties.
United States Census Bureau. Annual Estimates of the Resident Population: April 1, 2020 to July 1, 2024. U.S. Census Bureau, Population Division. Web. May 2025. http://www.census.gov/.
United States Census Bureau. B01001 SEX BY AGE, 2024 American Community Survey 5-Year Estimates. U.S. Census Bureau, American Community Survey Office. Web. 29 January 2026. http://www.census.gov/.
United States Census Bureau. B19013 Median Household Income, 2024 American Community Survey 5-Year Estimates. U.S. Census Bureau, American Community Survey Office. Web. 29 January 2026. http://www.census.gov/.
United States Census Bureau. “DP03 SELECTED ECONOMIC CHARACTERISTICS.” 2024 American Community Survey 5-Year Estimates. U.S. Census Bureau, American Community Survey Office. Web. 29 January 2026. http://www.census.gov/.
© Copyright 2026 Cubit Planning, Inc.