One of the most difficult pieces of data to find, and yet one of the most asked about, is religious affiliation and congregation information. There is only one source that I have ever found with any county level data available and that is the Association of Religion Data Archives.
The ARDA strives to democratize access to the best data on religion. Founded as the American Religion Data Archive in 1997 and going online in 1998, the initial archive was targeted at researchers interested in American religion. The targeted audience and the data collection have both greatly expanded since 1998, now including American and international collections and developing features for educators, journalists, religious congregations, and researchers. Data included in the ARDA are submitted by the foremost religion scholars and research centers in the world.
While ARDA has done its own survey work, they haven't done a nation wide survey of congregants since 2000. They are hoping to complete a new survey sometime this year, however. In the meantime the most recent data source with County level information that they cite on the website comes from InfoGroup USA. This is the result of data they collected during the 2009.
In addition to using Yellow and White pages to collect basic information, InfoGroup associates utilize denominational directories and web research to enhance the data with additional information including religious denomination, congregational size, worship attendance, church school size, and various church ministries. New congregations are identified through utility connects and other public sources. In the final stage of compilation, congregations are called by phone to verify and enhance listed information. Throughout all stages of compilation, associates attempt to collect names and email addresses for three congregational leaders: senior clergy (person in charge), youth clergy, and the music ministry contact.
This data is then assigned as belonging to a religious "tradition" as well as a religious "family". Religious Traditions categorize groups based on current religious beliefs and acceptance of the larger culture, but give little attention to denominational lineage. Religious Families organize religious groups based on their common religious ancestry or heritage, regardless of their current religious beliefs or social positions.
Below is the 2009 data for both Herkimer and Oneida Counties. It includes the traditions and families data breakouts.
