For newer TV's, you can get some over the air channels if you have an antenna ("bunny ears"). It's how I get TV channels at home. You can usually get major networks FOX, CBS, NBC, ABC, PBS. These channels will be in HD and there may be many others that are available.
However, signal availability is based on proximity to the broadcast tower. Since most towers are in urban areas, and most tracks are in rural areas, you may only get some of the channels above.
In 2010 (?) they converted broadcasts from analog to digital, so any older TV (basically any non-flatscreen + some exceptions exceptions) will not pick up digital signals without a converter box.