Out of curiosity, I check with the ballpark and asked them where they got the authority to prohibit firearms (as their policy states).

"Since the park is public property (owned by Lehigh County, a county within the state of Pennsylvania), and state preemption makes it illegal for any county to restrict the lawful possession of firearms, from where does the park management get the authority to prohibit firearms in the park carries for lawful purposes?"

The answer I received was this.

"As the sole tenant of Coca-Cola Park, we’ve had the ability with our lease with the County of Lehigh to create and provide rules for our fans who attend our games. Although the County owns the facility, we exclusively operate the ballpark.

We hire security for all of our events and we work closely with the local police and fire agencies. Although I understand your concern, we feel not allowing firearms helps to foster and create an environment where fans feel safer to enjoy the game with their families."