Nice work.
I think it’s more like 15-20K, but that’s not really based on hard data. Of course orgs aren’t super open to sharing the numbers… I bet insurance companies have the most complete data… but again, not sure how willing they would be to share it.
There are around 3000 in the Briggs Weekly Racing Series alone though:
If you are feeling ambitious, there’s a list of tracks here: tracks.kartpulse.com
It’s the most comprehensive one that I know of, but it is due some re-checking.