A query based on accounts with USA or United States in their profile location shows 127 posting/commenting, but there will be far more. Your own profile would not help me. Those running the Hive sites may see some location data about visitors, but not all will have accounts.
I have built the list of Brits over years based on research and tip-offs. I have over 800 in my file, but a lot are inactive and many only vote (probably automatically). If someone wants to do the same for the US then I will help where I can.
Only 127 active accounts sounds about right, lol. There are probably a ton of inactive autovoting accounts, lol. This actually tells me a bunch, thanks.
I have another query where I can list various locations in a country. Even with just a few states it finds many hundreds more who are possibly in the US, but then I have to check for false positives. e.g. I found one in 'usaquen' (Colombia), that contains 'usa'. I would guess that there could be over 300 posting in the US as many just give a city or state. It's not viable to search for two letter state abbreviations.
It's going to be hours of work to get more accurate numbers and I don't have the time right now.
This is why you need local knowledge. There will be communities that know who is around.