On the FM broadcast band, the FCC has reserved the lowest 20 channels, 201~220 (88.1~91.9MHz) for NCE stations only (called the reserved band), and channel 200 (87.9MHz) only for class D NCE stations (not including translatorss) forced to move by a full-power station.
On the TV band, individual channels are reserved, such that there is at least one in every area. In Canada, the CRTC operates the FM band this way as well, usually licensing at least one independent non-commercial station in addition to CBC English and/or French.
NCE stations may also operate on a non-reserved channel.