Interpreting 1906 county-level population data

In the 1906 Census of Religious Bodies: Religious Bodies Data [States & Counties] dataset, there are two columns (AZ8001 and AZ8002). I’m looking for county-level population data, what does each column mean? What data should I use for total population?

Your extract should have included a codebook with a data dictionary that defines all of the selected variables. Checking the codebook, it notes that columns AZ8001 and AZ8002 are the county-level total populations for 1900 and 1910, respectively.