God bless restless energy and the technology to re-format some information the UUA has on its website.
I stuffed the last UUA congregational certification numbers the membership numbers congregations use in making an annual report for GA, plus the latest available membership numbers for the churches that didn't certify, minus the Canadian congregations that have since disaffiliated from the UUA into a spreadsheet. Note: there is one existing congregation for which I cannot find good membership numbers.
That said, some facts.
There are 1059 congregations in or approaching membership in the UUA, including the Church of the Larger Fellowship (CLF) and twenty-five "emerging" congregations, the latter which I account as having zero members.
Together, this makes 157,267 adult members. The CLF is the biggest "congregation" (2762 members) but since it is in a category by itself, the "biggest church award" goes to First Unitarian Society, Madison, Wisconsin, with 1300 members.
Remove the CLF and the emerging congregations and you have 1,034 congregations.
The largest 3% (31 congregations; sized 587-1300) have 24,371 members.
The smaller 50% (517 congregations; sized 3-93!) have 23,310 members.
OK, I get desire for large congregations, though I do question the ability for a small-church denomination to accomplish this (including raising the money and managing jealousies) better than organizing more mid-sized churches that make up the middle two-thirds of the UUA collective membership. Not to mention the covenant made among the members of the UUA, and the resources left to fulfill it.
Enough for now. Want a statistic? Ask in the comments.