Today, programming from networks other than that with which the station maintains a primary affiliation are usually carried over digital subchannels, which increasingly since the mid-2000s, have allowed one of the major broadcast networks to expand their national coverage to markets where they would have previously either had to settle for a secondary affiliation with a full-power television station (which maintain transmitting power as high as 1,000 kilowatts and outputs a signal extending as far as from the transmitter site), or an exclusive or primary affiliation with a low-power station with more limited signal coverage (which maintain a reduced transmitting power not exceeding 100 kilowatts, with a more limited signal radius covering an area from the transmitter).