90.20 and 90.35 frequencies are interleaved in a number of places. There are even some frequencies that are shared between both services. Some places have run out of public safety frequencies and use IG (business/industrial) for public safety use, but those are not protected the same ways public safety coordinators attempt to for the PW channels they oversee. Some public safety agenices also use Part 22 (the old IMTS and paging) frequencies or frequencies carved out of Part 80 public coast (from MariTEL and Motorola). And some work with federal partners to use NTIA (federal) resources. You just never know where something will pop up - especially on VHF high band. Look for "very narrowband" (MotoTRBO and NXDN) technology to be more and more prevalent, especially in areas where there are many adjacent channel neighbors. MotoTRBO is a 2 slot TDMA technology that is a 6.25 kHz equivalent, so it more than meets the narrowbanding mandate.