Faithland – Mapping Religion Across America

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Religion has always played a central role in shaping American identity—not only spiritually but also culturally and geographically. Across the country, different denominations have taken root in distinct ways, forming patterns that reflect waves of immigration, migration, and local traditions. But how does this look when viewed through a cartographic lens?

Looking for new ideas, I turned to data from the Association of Religion Data Archives (ARDA). Their comprehensive datasets track religious adherence—the percentage of people in each U.S. county affiliated with a faith tradition—across a broad span of American history. I used ArcGIS to project these values to highlight patterns persisting and evolving.

These maps were generated using the Inverse Distance Weighted (IDW) interpolation. This method estimates values between known points, creating a smoother, more continuous visual space. Rather than showing a patchwork of counties, IDW helps illuminate regional trends—like spiritual landscapes—by softening hard political boundaries. It allows us to see where faith flows across state lines, pooling in valleys or thinning out on urban coasts.

Here’s the most recent snapshot, from 2010:

At first glance, it’s clear: Religion still plays a major role in many American communities, especially across the South, Midwest, and parts of the Mountain West. These areas glow with high adherence rates, reflecting what’s often called the “Bible Belt.” Meanwhile, lower levels of religious affiliation appear in the Pacific Northwest, New England, and urban centers along both coasts.

But one map only captures a moment. Now let’s see how Faithland has changed over the centuries (1890 – 2010).

Early in the 20th century, American religion was largely rural-and-small-town based with high adherence rates throughout the majority of the Midwest and Northeast. Moving from decade to decade, we find Catholicism growing in the Southwest—somewhat immigration-spurred—as growth increasingly in evangelical congregations also expands in the South. Late 20th and early 21st centuries have secularization evidenced in the Northeast and West Coast. The country becomes more religiously diverse, but also more religiously uneven.

One constant, however, is the sheer variety in religious presence across the map. In some counties—particularly in Utah and parts of Mississippi, Alabama, and the Dakotas—more than 70% of residents report formal religious affiliation. In others—particularly New England and the Pacific Northwest—fewer than 20% do.

These distinctions refer to American identity: its migratory patterns, cultural regions, and shifting moral landscapes. And while religion may be imperceptible on a satellite image, its existence—or absence—has charted communities over generations.