PRRI collected and aggregated data on religious diversity in America from 2014-2023, which contains 417,000 cases of Americans across all 50 states. The full data set was merged with county-level from the U.S. Census Bureau and the MIT Election Lab on 3,142 counties across all 50 states to produce a rigorous estimate of the religious demographics of every county in the United States with Montgomery County, MD coming out as the most religiously diverse in the country (Top 10 below).
According to PRRI, “As counties with populations over 10,000 cover about 98% of the total U.S. population, we report the top 10 counties for each religious group that had at least 10,000 residents. Because there is no measure of religious affiliation on any U.S. Census Bureau product, this PRRI Census of American Religion is the most comprehensive resource available on religious diversity in America.”
To measure religious diversity in the United States, this report uses an index developed to measure 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 and one religious group comprises the entire population of a given county.
Religious diversity is highest in major urban centers. The 10 counties with the highest religious diversity scores with populations greater than 10,000 residents are:
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- Montgomery County, Maryland (0.886)
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- Kings County, New York (0.883)
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- Nassau County, New York (0.876)
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- Montgomery County, Pennsylvania (0.873)
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- Contra Costa County, California (0.873)
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- Suffolk County, Massachusetts (0.869)
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- San Francisco County, California (0.868)
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- San Mateo County, California (0.865)
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- Rockland County, New York (0.865)
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- Queens County, New York (0.862)
The average religious diversity score by county in the U.S. is 0.615. Full report here. Featured photo shows the King Farm development in Rockville by @DronifyDMV