Yeah, that’s a lot of decline. And it’s not a small percentage, either. Look across the top portion of the state – there are many counties where the drop in religious adherents rate is at least ten percentage points (if not more) in just a ten year period of time. That’s really the norm in rural Iowa. That’s an important part of this story, by the way. These aren’t highly populous counties. It’s the rural part of the state that is leaving religion the fastest.

There are 99 counties in Iowa, I can find an increase in religion in just four of them. They are Adams, Lucas, Keokuk, and Louisa. None of those have a population of more than 11,000. Polk County is the largest county, it’s seen a 6% decline in religious adherents. Linn county is second – it’s seen an 8 point decline. It’s readily apparent from this data that religion is receding rapidly across almost the entire state.

But what religious traditions are the largest in Iowa? That’s what the map below shows us – I found the most popular religious tradition (in terms of number of total adherents) in all 99 counties. It’s a fascinating look at a state that is fairly religiously diverse.

[Not only is religious strength fading in Iowa, the form of it will surprise most. Evangelicals don’t have a large grip on the state, as it turns out; Catholics are more prevalent among the religious, followed by Methodists and ELCA Lutherans. Attempting to predict outcomes on the basis of evangelical strength (or “Christian nationalism,” a term that the media has seized) is an exercise in folly. — Ed]