I believe "open carry" is "legal everywhere due to the second amendment. I know in Ohio, it is legal to open carry a firearm. In the town I live, there used to be a day every year, can't remember what day, a whole bunch of people would walk through downtown with a sidearm. The law has become increasingly creative though, and will often times arrest someone for disturbing the peace, inciting panic, or being a public nuisance. If you even look like you're going to remove your weapon from your holster, they can also get you for brandishing.
Concealed carry is a lot easier 'cause no one knows.