American Religion Data Archive (Purdue)

URL: http://www.thearda.com/

Statistical data sets on the general U.S. population, religious groups, religious professionals, and individual denominations (the latter currently Nazarenes)
Churches and Church Membership data for states and counties for 1952, 1971, 1980 and 1990
Data may be downloaded in various formats
Codebooks include frequencies and percentages
A paper copy of the 1990 volume is in the Reference Room (BR 526.C481)