Following is the daily "Profile America" feature from the U.S. Census Bureau:
FM RADIO DEBUTS
Profile America — Wednesday, March 30th. FM radio is 75 years old. In March 1941, the first commercial FM station went on the air — W47NV in Nashville, Tennessee. FM — standing for frequency modulation — was first proposed in a scientific paper written by Edwin Armstrong in 1922. By 1934, he was demonstrating to network officials how FM was unaffected by static, like all the radio stations then on the air, which used AM, or amplitude modulation. World War II interrupted the advance of FM broadcasting, which surged in the 1960s when it began broadcasting in stereo. Today, some 83,000 people work in radio's 15,470 licensed stations, of which over 10,700 broadcast on the FM band. Profile America is in its 19th year as a public service of the U.S. Census Bureau.
Sources: Kane's Famous First Facts, 6299
First station/accessed 12/31/2015: http://www.dmwmedia.com/news/2012/03/05/happy-71st-birthday-to-fm-radio
Edwin Armstrong/accessed 12/31/2015: http://www.columbia.edu/cu/alumni/Magazine/Spring2002/Armstrong.html
Radio employment/NAICS 515112: http://factfinder.census.gov/faces/tableservices/jsf/pages/productview.xhtml?pid=BP_2013_00A1&prodType=table
Radio stations/accessed 12/30/2015: http://www.radiosurvivor.com/tag/number-of-radio-stations-in-the-united-states/
Profile America is produced by the Center for New Media and Promotion of the U.S. Census Bureau. These daily features are available as produced segments, ready to air, on the Internet at http://www.census.gov (look for "Audio" in the "Library" pull-down menu).
Source : prnewswire.com