The religion data used in our reports are from three sources:

• 1980 data were collected by the Glenmary Research Center and include statistics for 111 Judeo-Christian church bodies, including number of churches and adherents. These data originally appeared in Churches and Church Membership in the United States, 1980, published by the Glenmary Research Center. Most historically African American denominations are not included in the 1980 congregation and membership totals.
• 1990 data were collected by the Association of Statisticians of American Religious Bodies (ASARB) and includes statistics for 132 religious groups, including number of churches and adherents. These data originally appeared in Churches and Church Membership in the United States, 1990, published by the Glenmary Research Center
• 2000 data were collected by the Association of Statisticians of American Religious Bodies (ASARB) and includes statistics for 149 religious groups, including number of churches and adherents. These data originally appeared in Religious Congregations & Membership in the United States, 2000, published by the Glenmary Research Center. Historically African American denominations are not included in the 2000 congregation and membership totals.
• Data from the 2000 Religious Congregations and Membership Survey and the 1990, 1980, 1971, and 1952 Church and Church Membership collections can be downloaded free of charge from the ARDA's data archive.