Neustar has been successful in getting RFC1480-style domain names effectively discontinued as of maybe a decade ago (we're responsible for mil.wi.us here) and so any locality stuff under .fl.us is probably legacy stuff. They'd much rather sell people foo.us ...
If you're wondering about something in k12.fl.us, do a WHOIS and you'll find the Florida Dep't of Education. For other fl.us names, do a WHOIS on the name, and you'll find out what Neustar's got. I have a few <place>.ny.us delegations, but there's no new ones. There was a big kerfuffle in which Neustar demanded in the agreement that subregistries provide unlimited indemnification for their legal costs. It turned out that you could just cross out that clause and Neustar would accept it, but that news was not widely disseminated and many local registries just gave up. The .us zone still has some very crufty legacy stuff. The name iecc.cambridge.ma.us is still there as a CNAME, left over from something I registered in about 1991. There's no WHOIS for it, Neustar probably has no idea that I was the original registrant, and I have no idea how I'd even ask them to get rid of it. It's a dandy spamtrap, though. R's, John