The Census Bureau used the terms “bodies” and “denominations” synonymously, to signify religious organizations or groupings that included more than one local religious congregation.

In so doing, the Bureau adopted a Protestant American concept of what religious groups look like. As the historian Sidney Mead explained, a denomination is “a voluntary association of like-hearted and like-minded individuals, who are united on the basis of common beliefs for the purpose of accomplishing tangible and defined objectives.” In the American context, denominations sometimes competed with one another for members and influence, but groups such as the Presbyterians, the Methodists, and the Baptists acknowledged one another as branches of genuine Christianity. The Census Bureau then assumed that the institutional model followed by Presbyterians, Methodists, and Baptists was universal.

Not all religious groups fit into the American model of denominationalism. Catholics and Latter-day Saints, for instance, each claimed to be Christ’s one true church. Other Americans understood their religious affiliations and identities as matters of history, race, and ethnicity. While Census Bureau officials were aware of these fundamental differences in the ways that Americans understood their religious identities and affiliations, they classified everything from the “Roman Catholic Church" to the “Salvation Army” to the “Disciples of Christ” as “denominations.”

The Bureau also grouped certain denominations into broader theological “families," such as “Baptist” and “Presbyterian.” In the 1926 Census of Religious Bodies, the Bureau included 213 denominations. Of those, it grouped 155 denominations into 23 families and left 58 as “separate denominations.”

No taxonomy of religious groups is fully satisfactory. Many denominations do not fit neatly into a single denominational family, and their shared affinities change over time. In the early twentieth century, for example, a number of Pentecostal denominations emerged out of the Holiness movement.

In many instances, the Bureau’s taxonomy is helpful. It is useful to have the various Lutheran or Baptist churches grouped together. However, in order to help researchers better navigate the schedules of the census, this project has adopted the “Religious Groups” or families created by the Association of Religion Data Archives. The ARDA’s taxonomy of religious families includes the categories “Pentecostal” and “Holiness,” leaves fewer denominations uncategorized, and arranges denominations into fewer families.

If you are seeking the schedules of a particular denomination, select its denominational family and then select the individual denomination. If you are unsure where to locate a particular denomination, consult the ARDA Religious Groups, and check for uncategorized denominations in “Other Groups.”