Tools to play with the FCC's FM service contour data
The FCC provides data on all the FM transmitters in the US here: https://www.fcc.gov/encyclopedia/fm-service-contour-data-points
Direct link to the dataset: ftp://ftp.fcc.gov/pub/Bureaus/MB/Databases/fm_service_contour_data/FM_service_contour_current.zip
Data includes waypoints for the range of every FM transmitter.
Note: The maximum range of a transmitter is 119,468 m One degree of latitude is approx. 111,138 m One degree of longitude is between 111,320 m and 35,650 m (at (71.3776, -156.75375))
So the grid should be 2 degrees of latitude by 4 degrees of longitude