Don't know if any on SCF might be interested, but just across this USPS site that provides prospective bulk rate mailers with SMP (Simplified Mailing Process) information on the number of routes and customer deliveries for any state and county in the US and what an estimated cost would be for a bulk rate mailing to those recipients:
https://smp.usps.gov/Not particularly related to stamp collecting, I know, but I do find it an interesting link to gather any information on all of the different routes and customer counts (both business and residential) in any given community.