The FCC sets what parts of the bands can be used for phone and what’s CW or data only. Apart from that everything is basically a gentleman’s agreement. Since HF can go a long ways, there’s no point making local band plans for it. VHF and up is shorter range and some areas have different needs than others. There are frequency coordinators that handle the band plans and repeater pair assignments. Some states have more than one frequency coordinator for different parts of the state. Some frequency coordinators only handle repeater pairs and don’t publish a band plan.
I made some contacts on 20 & 40 meters. I had too much stuff to do today, so I was only able to be on for a couple of hours. 20 was very crowded in the NW US.