Because Adherents.com has such a large number of statistics and geography citations (over 45,000), we've prepared the following summary pages about the "Largest Communities" of various distinct religious groups. These pages are only about religious geography and statistics; they are not intended as sources of other information about the religious groups (such as history, doctrine, practice, etc.).
Remember: These lists do not present all the statistics in the Adherents.com database for these groups -- just summaries of where the "largest communities" in the world and/or U.S. are located.
There are three levels of geography these pages address: 1) nations; 2) U.S. states; and 3) U.S. counties.
There are two types of "large religious communities": 1) Large in raw numbers. A nation with ten million Buddhists has a "larger" national Buddhist community than a nation with ten thousand. 2) High proportion of the total population: A nation which is 90% Hindu (i.e., 90% of the population are Hindus) might be thought of as a "more Hindu" nation than a nation which is 80% Hindu, even if the raw numbers are far fewer in the nation with 90%.
Both of these methods of ranking "religious communities" within nations, states, and counties can provide some interesting perspectives about the geographical spread of a particular religious group.
With two types of ranking and three levels of geography there are six possible basic types of lists that the "Largest Community" pages present.
None of the pages have all of these possible lists. Lists are limited to those that we can present from available, reliably comparable data sets, and those that seem reasonably interesting and informative.
Not all religious groups are represented here, as not all groups are widespread enough to make such summary lists necessary. Jainism, for instance, is essentially only in one nation (India) in significant numbers. An idea of Jain geography (on the provincial level) can best be obtained from the records listed under "Jainism" in the main Adherents.com listings. If there were any Indian provinces or other nations in which Jains made up a remarkably high proportion of the population I might make a "Largest Jain Communities" page. But there are not. Nor are there significant Shinto communities outside of Japan.
"Largest Community" lists have been generated for some subgroups within Christianity. Many denominations only exist within a few states and no "Top 10" list is necessary. Other groups may be more widespread, but are too small and/or sociologically indistinct to be the basis for a summary list we thought would be interesting.
The lack of lists for subgroups of other major religions, such as Theravada Buddhists, Orthodox Jews, Shaivite Hindus, etc., should not be interpreted to mean these groups lack measurable and interesting social distinctiveness and distance from other branches within their respective broader religions. We simply have not had the time or sufficient data to generate such lists.