About Single Frequency Maps for AM and FM

The AM Maps by Frequency and FM Maps by Frequency tabs on the left open lists of AM and FM frequencies.  Click on a frequency to generate a map of the AM or FM licensed stations in the USA that are using the specific frequency.  AM options include daytime groundwave coverage and nighttime primary and secondary skywave coverage. FM results  include licensed FM stations, low power FM (LPFM) stations, and FM translator (repeater) stations.  These maps -- which show the nationwide distribution of stations on a specific frequency -- are useful for eyeballing broadcast radio service to a desired region.  They are also helpful for DXing (long distance listening), particularly on the AM broadcast band at night. Google Earth (or other KML browser) must be installed on your device.  We strongly recommend that you review the Making These Maps Work for You and Map Considerations tabs on the left, to learn how to make the maps function on your device. Please be aware that these maps are subject to change and correction without notice, and the contours shown may not always correspond to service contours and areas used in broadcast radio application processing.  Use the maps at your own risk, the FCC makes no representation of their suitability for any particular purpose.

Comments may be directed to Dale.Bickel, dale.bickel@fcc.gov.


AM Daytime Groundwave Service (0.5 mV/m + 2.0 mV/m)
AM Nighttime Skywave Service (0.5 mV/m)

  • 0.5 mV/m Daytime Protected Service Contour (light blue)
  • 2.0 mV/m Daytime Contour (light green)
  • 0.5 mV/m Nighttime Skywave Contour (Class A) - Primary Service (light blue)
  • 0.5 mV/m Nighttime Skywave Contour (Class B,C,D) - Secondary Service (light orange)
  • 0.5 mV/m Nighttime Skywave Contour from stations outside the USA (pink)
  • Some stations do not have a 0.5 mV/m skywave contour; transmitter site only will be shown.
  • Nighttime groundwave contours not presently available.  However, these will be the same
    as the daytime contours for stations operating with the same parameters day and night.

Map area:  




Low power Travelers' Information Stations in the AM band are not shown.  In the USA, 530 kHz and 1610 kHz are used for TIS stations, but they may be used on any AM frequency on a non-interference basis. (Also called "Highway Advisory Radio".)

Nighttime skywave service is dependent on several factors, including seasonal effects, atmospheric fading, and the sunspot cycle.  Secondary nighttime skywave service (orange contour) is also dependent on whether interference exists from other stations.  We make no determination here as to signal quality at any given location.

Nighttime skywave contours for stations outside the USA are based on notified parameters, some of which might be years out of date.  They are included to show potential limitations on U.S. AM broadcast station service, and to help identify such signals.  We do not guarantee accuracy for such records.  There are no plans to add daytime groundwave contours for stations outside the USA.

AM Records are divided into two sections - East (of 90° W Longitude) and West (of 90°W Longitude. . This division ensures that all records in that region are loaded into Google Earth for display.  For best results, allow one region's records to fully display before adding additional contour maps.

Contours are provided as-is, and users should be aware that the mapped information may not be identical to that used for radio broadcast application processing.


FM Single Frequency Maps

  • Protected Service Contours for FM and Low Power FM (LPFM) stations (light blue)
  • 60 dBu secondary service contours for FM translators (pink)
  • Stations outside the USA ae not included.


Map area:  



FM Records are divided into three sections - East (of 85° W Longitude), Central (between 85°, and 105° West Longitude) and West (of 105° W Longitude. . These divisions ensure that all records in that region are loaded into Google Earth for display.  For best results, allow one region's records to fully display before adding additional contour maps.

Contours are provided as-is, and users should be aware that the mapped information may not be identical to that used for radio broadcast application processing.


Map Considerations

FM Stations:  FM and Low Power FM (service codes FM and FL) service contours are plotted using light blue lines at the field strength applicable to the station class and location (see FM Station Classes and Service Contours for details).  FM translators' service contours are plotted in pink at the location corresponding to a 60 dBu field strength.

AM Daytime Groundwave Service Contour:  Daytime coverage is generally protected from interference caused by other stations within the 0.5 mV/m (millivolts per meter electric field strength) contour.  This will be shown by the light blue lines on the map.  During the daytime there is little to no skywave propagation, so skywave interference does not normally occur.  The 2.0 mV/m contour is also shown (green); for Class B stations this defines the nighttime protected service area.

AM Nighttime Skywave Service:  Coverage resulting from skywave propagation of AM nighttime signals is rather complex and we only touch on it briefly here.  In many cases, skywave coverage must be evaluated along with nighttime groundwave signals.  These maps do not consider all factors, thus, actual nighttime service may differ from that portrayed on these maps.  However, the maps do provide a useful approximation of what service may be anticipated.

  • For Class A AM stations, protected skywave coverage extends out to the 0.5 mV/m skywave contour, or 750 miles maximum, whichever is smaller.  These maps just show the nighttime skywave contour in blue for Class A stations.  Secondary service extends beyond the 0.5 mV.m contour.
  • For Class B AM stations, protected service extends out to the 2.0 mV/m daytime groundwave service contour (green), or the 2.0 mV/m nighttime groundwave service contour (not presently available).  Service beyond that 2.0 mV/m contour, out to the 0.5 mv/m conrour, is considered a secondary service that is not protected from interference from other stations. 
  • For Class C AM stations, protected service at night is the 0.5 mV/m daytime groundwave service contour, and secondary service (which is not protected from interference) can occur out to the 0.5 mV.m nighttime contour (orange).
  • Class D AM stations receive no protection for any nighttime service.  Most Class D stations that are permitted to operate at night do so at very low power levels and provide very local service.
  • Some AM stations do not operate with enough nighttime power to generate any 0.5 mV/m  nighttime service contour.  In such cases, only the transmitter site is shown on the nighttime map.
Again, there is no way that this brief summary can account for every station's nighttime interference-free coverage.

Making These Maps Work for You

To see any map, you must first have Google Earth (or another KML-capable Earth browser) installed on your device.  Preferably, Google Earth will be set up to recognize and open files ending in ".kml" and ".kmz".  Map processing can begin right away if Google Earth is already open or minimized in the background.  Some browsers may treat the initial link as a download and ask you what application to use to open the KML files.

If the links return text instead of opening Google Earth or your KML browser, then you may need to save the file before viewing. Return to the link, right click and "Save As" to your device as a text file with the extension of ".kml" (instead of ".txt"). Then open Google Earth, go to File | Open, and find the saved .kml file and select it.

Please be patient!  Because of the large number of station contours being generated and plotted, it can take a few minutes before all the service areas are rendered.  This is normal.

Don't plot too many too fast!  By keeping Google Earth open, you can select another option to add more radio station service contours.  But please allow one map layer (link) to complete before adding another layer (link).  Clicking too many too fast can cause downloading of station map data to halt without notice, resulting in incomplete maps.  Secondly, please be aware that Google Earth has an approximate limit of 10,000 "features."  It does not take very many nationwide map layers to reach this limit.


Information about AM and FM broadcast radio stations is available at the Audio Division on the FCC's website.  Information about TV stations is available at the Video Division.

FCC > Media Bureau > Audio Division



Wednesday, June 17, 2020