But religion influences local governments in less sensational ways. Some 21 states, for example, are requiring insurers under the federal health-care law to provide exemptions from contraception coverage for employers that object on religious or other grounds, according to the National Conference of State Legislatures. And 13 states in recent years have banned abortions past 20 weeks, a move influenced at least in part by religious views of when life begins. (Albuquerque, N.M., recently defeated a similar effort.)
With what is arguably the most widely observed holiday of the nation’s most popular religion right around the corner, now seems as good a time as any to look at the state of religion in America’s states and counties. All six of the maps and data below—which depict religious popularity, diversity and adherents—come from the “2010 U.S. Religion Census: Religious Congregations & Membership Study,” an every-decade research effort sponsored by the Association of Statisticians of American Religious Bodies, which gathers statistics for religious groups or scholars interested in such.
Most popular religion, by county
The Catholic church (blue) and Southern Baptists (red) dominate the map below, which marks the religion with the largest number of adherents in every American county. Blanketed red, the Bible Belt is alive and well. Members of the Evangelical Lutheran Church in orange can lay claim to a smattering of Midwestern and Western counties, while Mormonism (gray) is, unsurprisingly, the largest religion in every Utah county and in chunks of Utah’s neighboring states.
Largest non-Christian religion by state
Islam is the largest non-Christian religion in the nation, claiming 20 states scattered mostly throughout the Midwest and South. In the West, Buddhism is the largest non-Christian religion in 13 states. Judaism is the largest non-Christian religion in 15 states, mostly in the Northeast. Hinduism reigns in two—Delaware and Arizona. And the Baha’i claim South Carolina.
State size by total religious adherents
This map shows the U.S. if each state were sized according to the number of religious adherents who lived there.
Religious diversity, by county
This map shows how religiously diverse each county is. Brown and orange signify high diversity, while blue and blue-green signify those with very low religious diversity. Counties in many Western states and some New England states have high diversity, while there are pockets of low diversity throughout the middle of the country, Utah and the South.
Religious participation, by county
This map, made from RCMS data, shows the counties where religious participation per capita—adherents divided by population—was highest. Utah, the Midwest and parts of the South reign supreme. Religious participation was lowest in California’s Alpine County (4.3 percent), Hawaii’s Kalawao County (3.3 percent) and Nevada’s Esmeralda County (3.1 percent). The latter two have incredibly small populations, so are easily distorted by the religious inaction of a few. Click here to view an interactive map.
Total congregations, as a share of population
This table shows those counties with the highest number of congregations per 10,000 people. The numbers were lowest in New York’s Bronx and Richmond counties, Michigan’s Macomb County and Nevada’s Clark County, where there were only four congregations—defined as regular religious group meetings—per 10,000 people. Click here to view an interactive map.
CORRECTION: A previous version of this post misidentified the members of the Evangelical Lutheran Church.