Ever since car radios became available in the 1930’s, AM radio has been an integral part of the automobile experience. The Porsche 918 Spyder, scheduled for production in September 2013, will be the first production car in the United States not to come with an AM radio. The reason given is that the materials used to manufacture the car diminish AM radio reception. The Porsche 918 is a high-end sports car that will cost $845,000, so it hardly represents the mainstream. But I think it is clear that this is another step on the slide of AM radio into irrelevance in the United States.
Although there had been earlier tests, commercial AM radio really began in the United States in the 1920’s. AM radio (called medium wave radio pretty much everywhere else in the world) was the only consumer radio until FM radio was invented in the 1930’s. For a variety of reasons, FM radio didn’t become popular until the 1960’s and it took until the late 1970’s before it surpassed AM in popularity.
But even then AM maintained its own niche: low-powered local daytime stations and high-powered “clear channel” stations that blanketed multiple states in the nighttime. Interference from modern electronic devices (which affect AM over FM disproportionately) have taken their toll, but I think most of the rest of AM radio’s wounds have been self-inflicted.
For example, bandwidth of a radio station determines the quality of its sound. Before 1989, AM stations used a bandwidth of 15 kHz. After 1989, the bandwidth was reduced by the FCC to 10 kHz. Today, many radio station groups voluntarily use a bandwidth of 5 kHz. There have been moves for the FCC to make 5 kHz the official bandwidth and it is likely that it will eventually happen.
These bandwidth reductions, coupled with the poor design of modern AM radios (some support a bandwidth as small as 3 kHz!!), mean that AM radio sounds pretty awful today. Mix in the lack of local news or any local programming to distinguish individual AM stations, the preponderance of political talk radio (which tends to attract an older audience and repel a younger audience), and it is no surprise that AM radio is viewed today as a doomed technology.