Yes, but your first amendment right is violated if they do. The National security administration (NSA) monitors virtually all internet traffic. They do this to prevent terrorists and child perverts, etc.
I'm sure they use a software system to hash out keywords that could potentially deem the traffic a threat. If your message contains words associated with child porno or terrorist activity, it is usually reviewed by a human and if it is true illegal activity of that magnitude, they will escalate the threat or something like that.
I'm sure there are other government organizations that monitor, but your city, county & state governments don't have the authority to monitor.
There are hundreds of thousands of users on hundreds of forums just like RIU, and policing all these threads would be like 1 policeman trying to pull over 30-40 cars that are going 20 mph over the speed limit; it's just not gonna happen, there's too many; and since it's unconsitutional to start an investigation based on internet posting heresay; it is illegal for them to do so.
It's very safe to post here on RIU. Welcome to the forum!