It was on March 4, 1941 that the first FM station signed on in Nashville.  The station was known as “W47NV” and operated as a sister to the country powerhouse WSM (650).   It wasn’t until more than a year later when an FM signed-on by New York’s WOR (710) sold the first advertiser on the new technology – the watchmaker Longines-Wittnauer Co. sponsored the top-of-the-hour time check.

FM -- standing for frequency modulation -- was first proposed in a scientific paper written by Edwin Armstrong in 1922. By 1934, he demonstrated how FM was unaffected by static, unlike all the radio stations then on the air, which used AM or amplitude modulation. Critics said the idea was impractical. World War II interrupted the advance of FM broadcasting, which slowly began to gain popularity in the 1950s.

Today, there are nearly 11,000 radio stations around the nation -- close to six-out-of-ten of them operating on the FM band.