As the Iowa caucuses approach, here are some key facts about Iowans based on data from the PRRI Census of American Religion and American Values Atlas. PRRI survey data from 2022 finds:

• The median age of adults in Iowa is 45, younger than the median age for all Americans (48).
• The vast majority of Iowans identify as white (86%) and fewer than one in ten identify as Hispanic (7%), Asian American or Pacific Islander (4%), or Black (2%).
• When it comes to education, nearly four in ten Iowans (38%) have a high school diploma or less. Just under three in ten (27%) have completed some college and two in ten (21%) are college graduates, with 13% of Iowans holding post-graduate degrees.
• Iowans are somewhat evenly distributed across partisan lines, with approximately three in ten identifying as independents (31%), Democrats (28%), or Republicans (27%).
• One-quarter of Iowans identify as ideologically liberal (25%), compared with 36% who identify as moderate and 35% who identify as conservative.

According to the PRRI Census of American Religion 2022 update, statewide religious affiliation for Iowa is as follows:

Nationally, white Christians (including white mainline/non-evangelical Protestants, white evangelical Protestants,  and white Catholics) make up 42% of the U.S. population as of 2022. In Iowa, they account for about 6 in 10 residents (61%).

Iowa’s Religious Affiliation and Religious Diversity at the County-Level

Religious Diversity in Iowa

The 2020 PRRI Census of American Religion provides reliable county-level religious affiliation data. This includes our Index of Religious Diversity, which measures variations in the concentration of global religious populations. The index is calculated so that a score of 1 signifies complete diversity — every religious group is of equal size — and a score of 0 indicates a complete lack of diversity, where one religious group comprises the entire population of a given county. Nationally, the average religious diversity score by county is 0.625.

In Iowa, the counties with the five highest Index of Religious Diversity scores are: 1. Johnson County (0.764) 2. Dallas County (0.76) 3. Scott County (0.756) 4. Black Hawk County (0.748) 5. Linn County (0.747)

The five counties that rank the lowest on the Index of Religious Diversity are: 1. Sioux County (0.462) 2. Lyon County (0.465) 3. O’Brien County (0.485) 4. Pocahontas County (0.506) 5. Adams County (0.51)

White Christians in Iowa

As of 2022, about 6 in 10 Iowans (61%) are white Christians; this is largely unchanged from 2020, when 59% of Iowans identified as white and Christian.

White Christians are spread throughout the country but are most heavily concentrated in counties in the Midwest. As of 2020, the country’s highest concentration of white Christians in a county with more than 10,000 residents was found in Lyon County, Iowa (87%).

The top counties in Iowa with the highest concentrations of white Christians are:

1. Lyon County (87%)
2. Shelby County (83%)
3. Pocahontas County (83%)
4. O’Brien County (82%)
5. Osceola County (82%)
6. Monroe County (82%)

White Evangelical Protestants in Iowa

White evangelical Protestants make up 14% of the U.S. population as of 2022. See the concentration of white evangelical Protestants in Iowa by county:

The top counties in Iowa with the highest concentrations of white evangelical Protestants are:

1. Sioux County (45%)
2. Lyon County (44%)
3. Butler County (40%)
4. Montgomery County (39%)
5. O’Brien County (39%)

White Mainline/Non-evangelical Protestants in Iowa

White mainline/non-evangelical Protestants make up 14% of the U.S. population as of 2022. White mainline/non-evangelical Protestants are spread around the country but are most heavily concentrated in counties in the Midwest. See the concentration of white mainline/non-evangelical Protestants in Iowa by county:

The top counties in Iowa with the highest concentrations of white mainline/non-evangelical Protestants are:

1. Ringgold County (36%)
2. Calhoun County (35%)
3. Clayton County (35%)
4. Humboldt County (34%)
5. Monroe County (34%)
6. O’Brien County (34%)
7. Pocahontas County (34%)

White Catholics in Iowa

White Catholics make up 13% of the U.S. population as of 2022. As of 2020, the country’s highest concentration of white Catholics in a county with more than 10,000 residents was found in Dubuque County, Iowa (45%).

In Iowa, the counties with the highest concentrations of white Catholics are:

1. Dubuque County (45%)
2. Carroll County (28%)
3. Fayette County (27%)
4. Chickasaw County (26%)
5. Buchanan County (24%)

Hispanic Catholics in Iowa

Hispanic Catholics make up 9% of the U.S. population as of 2022. See the concentration of Hispanic Catholics in Iowa by county:

The top counties in Iowa with the highest concentrations of Hispanic Catholics are:

1. Crawford County (11%)
2. Buena Vista County (9%)
3. Marshall County (8%)
4. Woodbury County (7%)
5. Sioux County (5%)

Religiously Unaffiliated Iowans

Religiously unaffiliated Americans make up 27% of the U.S. population as of 2022. See the concentration of religiously unaffiliated Iowans by county:

In Iowa, the top counties with the highest concentrations of religiously unaffiliated Americans are:

1. Johnson County (39%)
2. Jefferson County (34%)
3. Story County (32%)
4. Dallas County (29%)
5. Union County (29%)
6. Lee County (29%)