Most likely yes. A good number of "larger" agencies have migrated to either P25 trunking systems or P25 conventional systems. However there are still a number of smaller communities that continue to use analog systems.
So it really depends on what you are going to monitor.
You can check the database reference section, looking up the state, then county of interest. It will show whether the system is P25.
Also whether you travel and do scanning is a consideration. It's a certainty that if you do, you will run across P25 systems.