Answer

The main source for religious data at the county level is the 2020 U.S. Religion Census, which "reports the number of congregations in every U.S. county equivalent for each of 236 faith groups." The Census is sponsored by the Association of Statisticians of American Religious Bodies (ASARB). 

The Association of Religion Data Archives (ARDA) also lets you search the 2020 U.S. Religion Census through its own County Report screen. Just select the desired State and County and click Start New Report. Each county report includes statistics for over three dozen faith groups, as well as a graph showing major religious traditions.

Screenshot of ARDA report