When I first started Edgewater Gold Radio, it began as a Part 15 station serving my condo community. Problem, nobody in my condo community listened, except one guy in 3L. The power allowed by the FCC without obtaining a license is extremely low. 1/10 of a watt for AM and about 1/40th of a watt for FM with lots of antenna restrictions. I lived in a heavily populated area with lots of buildings and concrete. This is no good for Part 15 broadcasting. My transmitter was on my terrace and the small antenna was only 15 feet off the ground. The result....awful. Barely a 1/4 mile signal. Unless you live in a flat area where you can have an effective ground system, if you are on AM my opinion is that it's not worth the effort. At most you can get about 1/2 a mile clearly. Unless you are doing this for hobby purposes only in my opinion, it's not worth the effort. Remember, you have to play by the FCC's extremely restrictive rules or you will be considered a "pirate" and can be subject to fines and lots of problems.
It's easier and a lot more gratifying to run an internet radio station. There are lots of issues with royalties but there are services such as Live 365 than can accommodate you and give you a start. It is also gratifying to see that you have actual listeners!