Editing Album-oriented rock (section)

===Freeform and progressive===
The album-oriented rock radio format started with programming concepts in the 1960s. The [[Free-form radio|freeform]] and [[Progressive rock (radio format)|progressive]] formats developed the tone for AOR [[playlist]]s for much of its heyday.

In July 1964, the U.S. [[Federal Communications Commission]] (FCC) [[FM Non-Duplication Rule|adopted a non-duplication rule]] prohibiting FM radio stations from running a [[simulcast]] of the programming from their AM counterparts. AM/FM affiliate station owners fought these new regulations, delaying enactment until January 1, 1967.<ref>Gent, George. "AM-FM Radio Stations Ready For the Great Divide Tomorrow" ''New York Times'' December 31, 1966: 39</ref>

The freeform format in commercial radio was created to program the FM airwaves inexpensively. Programmers like [[Tom Donahue (DJ)|Tom Donahue]] at [[KMPX (defunct)|KMPX]] in San Francisco developed stations where [[DJ]]s had the freedom to play long sets of music, often covering a variety of genres. Not limited to hits or singles, DJs often played obscure or longer tracks by newer or more adventurous artists rather than those heard on [[Top 40]] stations of the day. This new format caused albums, instead of singles, to be rock's main artistic vehicle in the 1960s and 1970s.<ref>{{Cite journal |date=1978 |title=The AOR Story |url=https://worldradiohistory.com/Archive-Ratings-Directories/RandR-AOR/R&R-AOR-Story-1978.pdf |journal=[[Radio and Records]]}}</ref>

With a few exceptions, commercial freeform had a relatively brief life. With more listeners acquiring FM radios, it became more important for stations to attract larger [[market share]] to sell more advertising. By 1970, many of the stations were instituting programming rules with a "clock" and system of "[[Rotation (music)|rotation]]." With this shift, stations' formats in the early 1970s were now billed as progressive. However, DJs still had input over the music they played. The selection was deep and eclectic, with a range of genres.