ɪfˈɛktɪv dᵻsˈɛmbɚ wˈʌn, nˈaɪntiːnhˈʌndɹɪd twˈɛnti wˈʌn, ðə dᵻpˈɑːɹtmənt ʌv kˈɑːmɜːs, wˌɪtʃ ɹˈɛɡjʊlˌeɪɾᵻd ɹˈeɪdɪˌoʊ æt ðɪs tˈaɪm, ɐdˈɑːptᵻd ɹˌɛɡjʊlˈeɪʃənz sˈɛɾɪŋ ɐsˈaɪd tˈuː wˈeɪvlɛŋθs fɔːɹ jˈuːs baɪ bɹˈɔːdkæstɪŋ stˈeɪʃənz: θɹˈiːhˈʌndɹɪd sˈɪksti mˈiːɾɚz ˈeɪthˈʌndɹɪd θˈɜːɾi θɹˈiː kˈeɪ ˌeɪtʃzˈiː fɔːɹ "ˌɛntɚtˈeɪnmənt" pɹˈoʊɡɹæmz, ænd fˈoːɹhˈʌndɹɪd ˈeɪɾi fˈaɪv mˈiːɾɚz sˈɪkshˈʌndɹɪd nˈaɪntiːn kˈeɪ ˌeɪtʃzˈiː fɔːɹ "mˈɑːɹkɪt ænd wˈɛðɚ" ɹᵻpˈoːɹts.
Effective December 1, 1921, the Department of Commerce, which regulated radio at this time, adopted regulations setting aside two wavelengths for use by broadcasting stations: 360 meters (833 kHz) for "entertainment" programs, and 485 meters (619 kHz) for "market and weather" reports.