调频广播:调频广播于1941年首次获得播出许可,这是目前美国听众人数最多的广播服务。由政府运营的,或非营利性质的及宗教性质的调频广播主要集中在88.1–91.9兆赫这20个频率上;而商业电台则通常使用92.1–107.9兆赫这80个频率[c]。当然,非商业电台也可以在商业电台频段上播出。由于调频广播是视线传播,因此调频广播的信号覆盖范围有限;除非出现非常罕见并且目前了解不足和不可预测的偶发E层传播现象,才有可能出现调频广播的长距离传播(英语:TV and FM DX)。受益于调频广播技术,由于调频广播电台使用比调幅广播电台和短波广播电台频率更高的频段,因此可以传输高保真的立体声广播;同时基于一种捕获效果(英语:Capture effect),可以大幅度减少频率相近且功率相似的两个调频广播电台之间的互相干扰。最初用于协助将调频广播电台信号覆盖到偏远地区的转播台现在也用于高清广播电台和调幅广播电台信号的转播,又是也会成为上述两种广播电台的主要信号发射源。目前,美国大部分的低功率电台都集中在调频广播频段上。
李·德富雷斯特受到了全美的关注,但是当时鲜为人知的是加利福尼亚州圣何塞的查理斯·赫罗德(英语:Charles Herrold),他在后世被认为是在美国第一个进行定期娱乐广播的人。1909年,赫罗德开始进行信号传输实验。在他将设备切换为改进版的弧变流器式发射机后,赫罗德于1912年7月宣布,他位于赫罗德无线与工程学院(Herrold College of Wireless and Engineering)的电台站将开始每周广播音乐会[34][35]。这些广播内容在第一次世界大战期间被迫中断,但是在一战结束之后,赫罗德便恢复了广播。现存的KCBS电台(英语:KCBS (AM))的历史就可以追溯到赫罗德的电台。
在1910年代中期,随着真空管式发射器的发明,音频传输的质量和可靠性得到了极大的改善。通过这次进步,李·德富雷斯特在纽约建立了2XG实验电台(英语:Radio 2XG)。在1916年10月成功举行的示范发广播里,德福雷斯特预言道“在不久的将来,每个大城市的音乐中心都会通过无线电话将当晚的音乐会传播到成千上万的家庭”[36]。而从次月开始,德富雷斯特的2XG电台就开始每日广播新闻和娱乐节目。而在当年11月7日总统选举之夜里,它还广播了选举结果[26]。但是,由于第一次世界大战的限制,2XG电台也在次年4月暂停运营。在2XG电台的活动期间,它启发了时任美国马可尼无线电报公司(英语:Marconi Wireless Telegraph Company of America)的合同经理大卫·沙诺夫。他撰写了他的第一份《广播音乐盒(Radio Music Box)备忘录》并提交给他的上级,建议公司筹建广播电台并出售接受设备。遗憾的是,他的建议并没有被采纳。因此,沙诺夫随后辞职并建立了美国无线电公司[37]。
关于这个时期美国其他广播电台的信息是比较有限的,但是在这个时期,还是有许多发明家偶尔进行了实验性的广播。例如,美国无线电与研究公司(American Radio and Research Company)在马萨诸塞州的梅德福山坡所建立的1XE电台(英语:WGI (radio station))。早在1916年3月,该电台就偶尔被用来进行语音和音乐广播,尽管在当时它被描述为仅是公司的主要工作里的“偶然事件”[38]。此外,乔治·坎农(George C. Cannon)也报告道,从1916年12月到1917年2月,他在他位于纽约州新罗谢尔的家里通过其特殊业余电台2ZK进行新闻及娱乐广播,并保持了一份“从晚上9:30到晚上10:30的定期节目表”[39]。
In October 1919 Frank Conrad began semi-regular broadcasts from his experimental station 8XK, located at his home in Wilkinsburg, Pennsylvania.[47]
The Precision Equipment Company's 8XB in Cincinnati, Ohio began regular broadcasts in early 1920. On October 31, 1920 the Randolph Wurlitzer Co. presented a concert of Victor phonograph records over the station.[48]
6XC, the "California Theater" station established by Lee de Forest in San Francisco, California, began daily broadcasts in the spring of 1920.[49]
AMRAD, in Medford Hillside, Massachusetts, began a limited series of broadcasts over experimental station 1XE in the summer of 1920.[50]
In August 1920 the Detroit News began daily broadcasts over its "Detroit News Radiophone" station, 8MK. Station WWJ traces its history to this station.
Westinghouse's KDKA in East Pittsburgh, Pennsylvania made its debut (as 8ZZ) broadcasting election returns on November 2, 1920, followed by daily broadcasts the next month.[51]
^Castañeda, Mari. "The importance of Spanish-language and Latino media." Latina/o communication studies today (2008): 51-68.
^ Jorge Reina Schement, “The Origins of Spanish-Language Radio: The Case of San Antonio, Texas", Journalism History 4:2 (1977): 56–61.
^Andrew Paxman, "The Rise of US Spanish-Language Radio from Dead Airtime to Consolidated Ownership (1920s–1970s)". Journalism History 44.3 (2018).
^ Félix F. Gutiérrez and Jorge Reina Schement, Spanish-Language Radio in the Southwestern United States (Austin: UT Center for Mexican American Studies, 1979).
^Todd Chambers, "The state of Spanish-language radio." Journal of Radio Studies 13.1 (2006): 34-50.
^Dolores Inés Casillas, Sounds of belonging: US Spanish-language radio and public advocacy (NYU Press, 2014).
^The Wireless Age Volume 10. Macroni Publishing Corporation. 1922: 25 [2020-04-24]. (原始内容存档于2021-12-06). Prior to January 1923 the "K-W" dividing line ran along state borders north from the Texas-New Mexico border.
^"Experiments and Results in Wireless Telephony" by John Grant, The American Telephone Journal. Part I (页面存档备份,存于互联网档案馆): 1907-01-26, pp 49-51; Part II (页面存档备份,存于互联网档案馆): 1907-02-02, pp 68-70, 79-80.
^History of Radio to 1926 by Gleason L. Archer, 1938, p 112-113. The exact date and contents of Sarnoff's first "Radio Music Box" memo has been the subject of controversy. The most commonly accepted date is November 8, 1916, although some later RCA publicity claimed that it was actually written on September 30, 1915.
^"Camp Jackson Has Its Own Daily Newspaper", The (Columbia, South Carolina) State, 1918-03-25, p 3. This article's sub-headline reads: "Gets Messages From Arlington and in a Few Minutes Copies Are Posted on One Hundred and Thirty-five Bulletin Boards at the Camp".
Kahn, Frank J. ed. Documents of American Broadcasting (Prentice-Hall, 4th ed.,1984), Focuses on regulatory issues
Aitkin Hugh G. J. The Continuous Wave: Technology and the American Radio, 1900-1932 (Princeton University Press, 1985).
Barnouw Erik. The Golden Web (1968); The Sponsor (1978); A Tower in Babel (1966). (all Oxford University Press); Comprehensive history of American broadcasting
Covert Cathy, and Stevens John L. Mass Media Between the Wars (Syracuse University Press, 1984)
Cox, Jim. Radio Journalism in America: Telling the News in the Golden Age and Beyond (McFarland, 2013)
Cox, Jim. American Radio Networks: A History (McFarland, 2009)
Cox, Jim. Radio After the Golden Age: The Evolution of American Broadcasting Since 1960 (McFarland, 2013)
Craig, Douglas B. Fireside Politics: Radio and Political Culture in the United States, 1920-1940 (2005)
Dimmick, John, and Daniel G. McDonald. "Network radio oligopoly, 1926-1956: Rivalrous imitation and program diversity." Journal of Media Economics (2001) 14#4 pp: 197-212.
Douglas, Susan. Inventing American Broadcasting, 1899-1922 (Johns Hopkins University Press, 1989)
Dunning, John. On The Air: The Encyclopedia of Old-Time Radio (Oxford University Press, 1998)
Gibson George H. Public Broadcasting; The Role of the Federal Government, 1919-1976 (Praeger, 1977)
Hilmes, Michele. Only Connect: A cultural history of broadcasting the United States (Wadsworth, 2007, 2nd ed.)
Jackaway; Gwenyth L. Media at War: Radio's Challenge to the Newspapers, 1924-1939 (Praeger, 1995)
Lackmann, Ron. Encyclopedia of American Radio (2nd ed. 2000), Over 1000 short articles; not much changed from first edition which was entitled Same Time...Same Station (1995).
Lazarsfeld Paul F. The People Look at Radio (University of North Carolina Press, 1946)
Leblebici, Huseyin, et al. "Institutional change and the transformation of interorganizational fields: An organizational history of the US radio broadcasting industry." Administrative science quarterly (1991): 333-363, Highly influential article. in JSTOR (页面存档备份,存于互联网档案馆)
McCauley, Michael P. NPR: The trials and triumphs of National Public Radio (Columbia University Press, 2005)
McChesney; Robert W. Telecommunications, Mass Media, and Democracy: The Battle for the Control of U.S. Broadcasting, 1928-1935 (Oxford University Press, 1994)
Maclaurin W. Rupert. Invention and Innovation in the Radio Industry (Macmillan, 1949; reprinted by Arno Press, 1971)
McCourt; Tom. Conflicting Communication Interests in America: The Case of National Public Radio (Praeger, 1999) online (页面存档备份,存于互联网档案馆)
Ray William B. FCC: The Ups and Downs of Radio-TV Regulation (Iowa State University Press, 1990)
Rosen Philip T. The Modern Stentors; Radio Broadcasting and the Federal Government 1920-1934 (Greenwood, 1980)
Slater Robert. This . . . is CBS: A Chronicle of 60 Years (Prentice-Hall, 1988)
Smith, F. Leslie, John W. Wright II, David H. Ostroff; Perspectives on Radio and Television: Telecommunication in the United States (Lawrence Erlbaum, 1998)
Sies, Luther F. Encyclopedia of American Radio: 1920-1960 (McFarland, 2d ed. 2 vols., 2014)
Sterling, Christopher H., and Kittross John M. Stay Tuned: A History of American Broadcasting (LEA/Routledge, 2002, 3rd ed.).
Sterling, Christopher H., and Michael C. Keith. Sounds of change: A history of FM broadcasting in America (Univ of North Carolina Press, 2008)
Terrace, Vincent. Radio's golden years: The encyclopedia of radio programs, 1930-1960 (1981)
White Llewellyn. The American Radio (University of Chicago Press, 1947)