Portland, Oregon's earliest AM radio stations appeared in the early twenties. One of those early stations was Oregonian Publishing's KGW. Others included KDYQ, KFAB, KGG, KGN, KQY and KYG. After the first two decades of commercial radio involving shared and swapped frequencies, the AM dial entered a more stable era beginning in the early forties. Some of the key stations at that time included KGW (620), KOIN (970), KWJJ (1080), KEX (1190), KXL (1450) and KALE (1330).

By the late seventies, KGW was among the last successful AM top 40 stations in America, as music fans moved to FM. In the late fifties KEX played hit music. Their long running morning show was Barney Keep, who did the show from 1944 to 1979. Bob Swanson, who did a midday talk show, was another long-running jock on the station from 1966 to 1996. In the fifties, Portland's top station was KISN (910). By the sixties KGW had become a leading station, playing top 40 hits, known as "Super 62 KGW." Another top 40 station in the sixties was KYMN (1520).

While in many major markets freeform radio got its start on the emerging FM dial in the late sixties, Portland's first progressive rock station happened on AM. It was KVAN (1480), first appearing in the summer of 1967. The independent station was owned by Cathern Murphy, who was eventually forced by the FCC to sell the station in 1974 due to not meeting commission requirements. It sold to Howard Slobodin, who held the station for five years and was able to get the station on the air at night beginning in 1975. By the end of the decade it had become top 40 station KARO under new ownership. Other rock stations to follow on FM were KGON, KUFO, KZRC and KINK.

In the late seventies disco became a national trend which inspired the former KOIN to flip to all disco as KYTE-AM. But not only did the disco trend only last a few years, music fans were moving to FM by that point. As the eighties unfolded, top 40 station KKRZ (100.3) took the market crown. The only high-rated AM station playing music by that point was KEX, which had moved to adult contemporary. Both KKRZ and KEX were owned by Great American Broadcasting. The other big station on the AM band was news/talk KXL (750), owned by Kaye-Smith.

One of the most resilient stations over the years has been adult alternative station KINK (101.9). In the eighties it was owned by King Broadcasting, experimenting more with new age. In the nineties it was owned by American Radio Systems and eventually CBS Radio, as a successful adult alternative. American Radio Systems, along with Jacor were the first big radio owners in the market as a result of the Telecom Act of 1996, which loosened ownership limits, allowing big companies to buy several stations in a market.

Throughout the nineties KKRZ remained not only the leading top 40 station in town, but also the overall number one station in the market. Other high-rated stations in the nineties included country station KUPL (98.5), country competitor KWJJ (99.5), adult contemporary station KKCW (103.3), oldies station KKSN (97.1), news/talker KXL (750 AM), full service music/talk station KEX (1190 AM), active rocker KUFO (101.1) and classic rocker KGON (92.3). Alternative station KNRK (94.7) has not have strong enough signal coverage to gain high ratings, but has been influential in introducing new music to Portland since the mid-nineties. It is the flagship station of the local gone national band Everclear.

In the 2000s CBS Radio owns six stations in the market: KUPL (country), KINK (adult alternative), KUFO (rock), KVMX (80s), KLTH (adult contemporary) and KCMD-AM (comedy). Entercom is also a big player, owning KWJJ (country), KGON (classic rock), KYCH (adult hits), KNRK (alternative), KRSK (hot ac), KFXX-AM (sports) and KSLM (talk). Clear Channel owns five stations in the market: KKCW (adult contemporary), KEX-AM (news/talk), KPOJ-AM (talk), KKRZ (contemporary hits) and KRVO (classic hits). Rose City Radio holds formidable challengers KXJM (contemporary hits) and KXL-AM (news/talk).

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