I wanted to make sure I wasn't talking out of my ass about the posted signs, so I looked up the regulations for where I was from (New York): https://www.dec.ny.gov/regulations/2442.html#posted

But to be clear about my anecdote, I wasn't doing anything wrong and wasn't actually arrested. My family's property bordered the property I "trespassed" on, and the guy called the cops on me, a 10 year old, instead of just telling me to leave. The cop showed up and basically just scared me and said he didn't want to come back out there.