Each state has different laws on what, who, and where you can record. My state's laws allow recording of anything in 'public'. No restrictions except that you cannot use sound when recording (not admissible in court). You can't record people by looking in their windows, or by using ladders to look over fences, or in any place where 'privacy' is assumed, (like a public restroom).
Our local police force just spent mega bucks to give every patrolman a body camera. I'm sure I'm a star in at least one of those recordings when I called the police about the looters/squatters across the street. Hope I looked good.
I have security cameras around my house which monitor my yard, the street out front, the driveway, etc. I can see anything that happens in public. It's great to keep track of 'suspicious' people and the police have requested some of my tapes for their files.
With the popularity of the new Drones, it's getting even more complicated to follow the law. An apartment manager in my city was using a drone to keep track of the renters, by flying the drone with a go-pro camera up over their second floor balconies and filming in their windows. A big no-no on his part. That one is still in the DA's hands as to whether or not to charge him with invasion of privacy.
Camera's all over now, on houses, in the stores, on drones, in everyone's hands who owns a cell phone. I think George Orwell was right, Big Brother is really watching!