I got asked this question a couple times when mentioning that I always have the police radio playing at home.
There are a lot of (totally legal!) ways to listen in on your local gang in blue’s radio communications, but the easiest is to use Broadcastify.com, a service run by RadioReference (awesome boomer RF resource). It’s free, works pretty well, and is so easy to get running that your ACAB grandma could figure it out.
Click your state, scroll or Ctrl+F for your locality, then click play. Police channels, fire channels, public safety, etc.
If the department you’re looking for isn’t listed it may be for a couple reasons. If they’re using encryption in addition to just digital trunking, then it’s unlikely anyone will be streaming them to Broadcastify. But if they don’t use encryption (and you can use RadioReference to look up what system every PD is using!) it may just be that no one is currently streaming that specific PD. Maybe it’s a really small town, or maybe the person streaming it before is under arrest lmao.
Which is actually excellent, because now you can learn about RTL-SDR and start capturing their radio yourself! Gone are the days when you need to drop $500 on a police scanner just to handle trunking. You can spend less than $30 on an RTL-SDR dongle and couple that with free software. The actual set-up is beyond the scope of this quick post, but there are a lot of articles out there on how to do it, and it’s really fun.
Sadly most police in high-urban areas are moving to encrypted radio so for anyone living near bigger populations they might not get as much use out of it. Personally I usually only get some backup frequencies and maybe sheriff dispatch or fire department, otherwise most emergency services are switching to the same system (high-band Motorola networks) for ‘disaster preparedness’. I still encourage people to check of course and if you’re anywhere else you definitely should be able to listen in on local comms.
Once all departments make the switch to LTE we’ll basically lose that entire monitoring surface, which is why it’s really important to develop novel ways of tracking them now.