American Religion Data Archive
Funded by the Lilly Endowment, Inc. it "acts to preserve quantitative data on American religion, to improve access to this data, to increase the use of the data, and to allow comparisons across data files. The ARDA collection includes data on churches and church membership, religious professionals, and religious groups (individuals, congregations and denominations)." Files can be browsed or searched. Provides religious congregation and membership maps and reports. List of other related internet sites is also available.