Religion Comparison

I am researching the impact of religion/religiosity on the American Civil War. As a part of that research I would like to compare data of religious affiliations in the 19th Century (particularly the 1860s) and today. I have searched the data using descriptors such as “religion” and “religious”. So far I have come up with nothing. I am thinking that perhaps the data that I’m seeking is available but embedded within a category that I’m not considering. I would appreciate any help that you can provide in directing me to helpful places. Thank you!
Dave Fetterman

You are correct that the IPUMS USA data does not contain any information on religion. The U.S. Census has never collected information on the religion of individuals. However, IPUMS NHGIS has data on “religious bodies”, which are based on surveys of religious organizations, not of people, summarized by state and county, 1850-1952. You can read more about those data here: Overview of NHGIS Datasets | IPUMS NHGIS. Prior to 1900, some of these data were gathered during the decennial census, though again only from religious organizations. I found this paper from Pew which gives a history of these data collections.