The first step to starting your own AM station is applying for a federal license. It takes time, as the Federal Communications Commission accepts applications at only during certain times. Watch the FCC website for announcements about when the next window opens. You may be competing with hundreds of other applicants, so don't make any errors that could cost you your chance.
Even low-power stations -- except for college stations -- require an FCC license. To apply for a license, you need an FCC registration number. You can register through the agency's website or by submitting FCC Form 160 by mail. If you do not include the registration number on your radio-license application it will be rejected. To apply for a new license, complete FCC Form 302-AM and Form 159 electronically. The filing fee is $635. If you plan to build a new station, you must submit Form 301 with a $3,870 fee.
All AM radio stations broadcast on the frequencies from 540 to 1700 kilohertz. One of the obstacles to new AM stations is that you have to pick a frequency that won't interfere with other stations. This includes stations elsewhere in the country that use the same frequency, and adjacent radio channels, those 30 kHz above or below your own. Your application has to demonstrate that you won't cause interference problems. The FCC says it usually takes an expert to provide a convincing analysis.
The FCC strongly recommends that you wait until you have a license in hand before buying equipment. You will, however, have to figure out what equipment you're going to use and submit that information on your application. You'll need to give the FCC the location of your planned transmitter and studio, along with the antenna coordinates down to the seconds of longitude and latitude. The FCC wants to know the height of the antenna radiator, the overall antenna height and many more technical details.
Building a station from the ground up requires a lot of hardware. You must find a location for a studio, buy a transmitter and set up a radio tower, along with all your other equipment. The alternative is to buy out someone who already owns a radio station and a broadcast license and then air your own programs. With this approach, you sign a contract to buy the station, then file Form 314 with the FCC. If the agency rejects your application, you can't close the deal. At tims, applying for a license in a given area is impossible. The FCC will not accept an application for permisssion to broadcast in an area with no available frequency.