I'll add Austin, Texas to the discussion, as I lived there in the 1960's and early 70's.
Austin's original TV station was KTBC/7, owned by Lyndon Johnson and his wife. KTBC went on the air in 1952 with a mix of all the networks at the time. This hodge-podge continued as the sole network TV option in Austin for the next 13 years.
In 1965 KHFI/42 went on the air, but it was also a mix of all the networks.
The two-station, "all networks" scenario was quite a scheduling mess. You had to carefully consult TV Guide as otherwise you would have no idea on which channel a particular network's show would air. And since the three network timeslot schedules didn't match, shows were often delayed by days or even weeks before airing in Austin. Many shows were run on Sunday afternoons, or in the case of KTBC, after the 10pm news (CBS did not have late night programing then.) Making things worse was that many of the delayed shows were run from mediocre 16mm film prints that were sent to the stations, or for shows originally live or on videotape, kinescopes were used (horrible quality even by 1960's standards.)
The situation began to resolve itself in 1968 when KHFI got the exclusive NBC affiliation (Wikipedia has it as 1966 which is incorrect, as KHFI was still running the network hodge-podge into 1968.) KTBC then became mostly CBS, with some of the more popular ABC shows in the mix.
Austin finally got three separate network affiliates when KVUE/24 signed on in 1971.
In 1973 KHFI/42 moved to channel 36 and greatly increased its power. Call was also changed to KTVV. The current KXAN call is from the late 1980s.
KTBC remained a CBS affiliate until 1995 when it flipped to Fox as part of the New World Communications/Argyle merger. It is now a Fox O&O. Fox's original Austin home had been KBVO/42, which signed on in 1983. KBVO wound up with the CBS affiliation in 1995 and changed its call to KEYE.
Also of interest in Austin: The "educational" NET and later PBS station was KLRN/9, which went on the air in 1962 and was shared with the San Antonio market. The transmitter was northwest of New Braunfels, so it dropped a decently viewable signal into both cities. This situation continued until 1979, when Austin got its own PBS, KLRU/18. The two stations were pretty much a simulcast until the KLRN/9 transmitter was moved all the way into the SA market a few years later.
Austin is sandwiched in between the Waco, San Antonio and Houston markets, which limited VHF allocations there. Concerns over the viability of UHF stations helped delay the establishment of additional stations. KHFI/42 hit the air right after the "All Channel Receiver Act" went into effect, so new sets could tune all 82 channels. In addition, UHF converters were in abundant supply at various Austin stores and electronics dealers; I recall stacks and stacks of them at the old Gulf-Mart on Burnet Road. Lots of TV viewers wanting the additional channel option snapped these up, and they worked reasonably well.
Austin was oddly late to the three network/three channels game, as other smaller Texas cities such as Corpus Christi and Amarillo had been three network station markets for many years (since 1957 in Amarillo's case.) On the other hand, the Waco market didn't get three affiliates until KXXV signed on in the mid 1980's. Some political shenanigans on Lyndon Johnson's part also kept competition out of the Austin market for a number of years.
Should note that rooftop TV antennas aimed to the southwest were a common sight in Austin in the early TV days as they would bring in fuzzy but viewable signals from the three network affiliates in San Antonio.