No single event or station introduced radio broadcasting to the entire United States. Instead, broadcasting activities evolved in many locations, slowly entering the public consciousness. By early 1922 there was enough organized activity for various publications to begin putting together national lists of stations that were providing broadcasts intended for the general public. However, because of the scattered nature of the activities, no single list at this time, including this one, was able to keep up with all the stations on the air. (Also, note that the ranges listed for many of these stations appear to be very optimistic, even for optimum nighttime conditions).

The list below was prepared while U.S. broadcasting was going through an important transition. Initially there had been no restrictions on which radio stations could broadcast programs intended for the general public. But on December 1, 1921 the Bureau of Navigation issued a new regulation, which restricted non-government broadcasting to only those stations which held a Limited Commercial licence plus an authorization to use the Entertainment wavelength of 360 meters (833 kilohertz), and/or the Market and Weather wavelength of 485 meters (619 kilohertz). It took a few months for all the stations to fall in line with this new broadcast service regulation, which means that in the list below many stations from other licence categories are still included. However, these stations were now required to either get Limited Commercial licences or stop making broadcasts. (A review of how you can determine a station's licence classification from its callsign is included at the close of this list).

Popular Science Monthly, March, 1922, pages 72-73:

First  American  Radio  Charts  Show  Nation  Is  Now  Blanketed  by  Wireless  News  and  Music

You'll  Find  in  These  Maps  the  Broadcasts  that  You  Can  Hear
How Radio Reaches You Wherever You Are
YOU have never before seen maps of the United States like those printed here. They are the first American radio charts.
    Only a few months ago, POPULAR  SCIENCE  MONTHLY started the present national wireless craze going, with our already famous "Wake Up to Wireless!" message, written by Armstrong Perry. The nation IS wide awake to-day. Nobody can predict how many hundreds of thousands of families will soon be enjoying the most romantic recreation of modern times.
    POPULAR  SCIENCE  MONTHLY has compiled these pioneer radiotelephone broadcasting charts in order to show just what vocal entertainment a good receiving-set can give.
    If you wish further information about wireless or broadcasting stations, write to the Question and Answer Department of POPULAR  SCIENCE  MONTHLY.
HERE is the first chance ever given the people of America to see at a glance how many important broadcasts of wireless music, news, and entertainment can now be heard in every part of the country.
    After securing direct reports from dealers and amateurs in all parts of the United States, and after excluding numberless smaller stations, POPULAR  SCIENCE  MONTHLY has selected twenty-two points and has charted their location and "normal range on the accompanying radio map. One or another of these stations can, with proper equipment and favorable local conditions, be heard easily and regularly in 48 states of the Union.

How to Find Your Program

    To find out what radio entertainment you may normally expect to receive in your locality, simply complete in pencil on the map the circles partially indicated by the dotted lines. With the proper receiving set, and provided atmospheric conditions are right, the chances are in favor of your hearing the stations within whose radius thus charted your particular town falls.
    Daily and nightly radio programs may possibly be heard over even greater distances than are here indicated, but don't forget that local conditions of all kinds may cut down the number of stations you are likely to hear in your district. In some regions you may have difficulty because of too many stations using the air at once. Before purchasing a receiving set, supplement the information given here by consulting an amateur in your neighborhood, and by requiring, if possible, a demonstration of the set by the dealer.
    Finally, if the outfit you are using is one of the low-priced, crystal detector sets, remember to divide the distances shown on the map at least by 10, in order to get a reasonably accurate estimate of the radius in which any given station's broadcasts may be heard by you.
    Having found on the map the cities containing radio stations that you are likely to hear in your district, you can secure from the following paragraphs definite information about these stations. eastern map
THE following stations in North Atlantic and New England states give extensive broadcasting service:
    Newark, N. J.--Westinghouse Electric & Manufacturing Co. station (WJZ). Wave length, 360 meters. Program of news and concerts every evening at 8.05. Children's hour every Friday at 7.15 P.M.
    Pittsburgh, Pa.--Westinghouse station (KDKA). Wave length, 330 meters. Washington Observatory time broadcasted daily, except Sunday, at 8 P.M. Government market and New York stock reports at 8.05 P.M. Special musical program, 8.30 to 9.30 P.M. Organ recital every Sunday at 4 P.M.
    Springfield, Mass.--Westinghouse station (WBZ). Wave length, 375 meters. Concerts and musical programs every Sunday, Monday, Wednesday, and Friday at 8 P.M.
    Medford Hillside, Mass.--American Radio and Research Corporation station (1XE). Wavelength, 350 meters. News, concerts, and music every weekday evening, with sermons every Sunday.
    Hartford, Conn.--Station of C. D. Tuska Co. (WQB), with a wave length of' 425 meters. Concerts on Tuesdays, Thursdays, and Saturday evenings.
    Union College, Schenectady, N. Y.--Irregular program of music.
    Roselle Park, N. J.--Station of the Radio Corporation of America (WDY). Range 1000 miles.
    IN the Southern section these stations, among others, are audible:
    Washington, D. C.--Government and private stations. Correct time broadcasted at noon and 10 P.M. daily from Arlington Navy Station (NAA) with a wave length of 2650 meters. The White & Boyer station, on Tuesdays and Fridays from 7.30 to 9.30 P.M., broadcasts concerts as well as short lectures on radio.
    Atlanta, Ga.--Carter Electric Co. station (4CD). Range 200 miles. Music, and news service Sundays, Tuesdays, and Thursdays, from 7.30 to 8 P.M.
    Dallas, Texas.--Police and fire department station (WRR). Wave length, 450 meters. Weather forecast, local news, and other information at 7.30 P.M. daily. Concerts every evening, 8.30 to 9.
    Austin, Texas.--State University station (5ZU). Wave length, 375 meters. Results of athletic contests, local news.
    Houston, Texas.--Numerous amateur radiotelephone broadcasting stations with ranges up to 60 miles. western map
WORKING westward on the map, the following are the most important stations generally heard by amateurs who have reported:
    Westinghouse Station at Chicago, Ill. (KYW). Wave length, 360 meters. Grand opera program every evening except Friday and Sunday during opera season. Concerts Friday evening.
    Cincinnati, Ohio.--Station of Precision Equipment Co. (8XB). Wave length, 375 meters. All evening on Monday, Wednesday, and Saturday--music, vaudeville, and sport reports.
    Madison, Wis.--State University station (9XM). Weather reports in code and then in voice, daily except Sunday at 12.35 P.M., with a wave length of 375 meters. On Fridays, special music at 7.30 P.M., at 800 meters. Same music at 8.15 at 375 meters. Various entertainments during remaining part of evenings at wave lengths between 330 and 375 meters.
    Lincoln, Nebr.--State University station (9YY). Has widest range in that section. Concerts every evening.
    Kansas City, Mo.--Station of the Western Radio Co. (9XAB). Market reports and weather forecasts at 11.30 A.M. and 2 P.M., on 375 meters. Concerts in the evening.
    Denver, Col.--Station of the Reynolds Radio Company (9ZAF). News twice a day. Concerts on Sunday evening.
    San Francisco, Calif.--Concerts by various commercial and hotel stations every evening in the week. California Theater to broadcast performances nightly at 360 meters.
    Los Angeles, Calif.--Station in Hamburger's department-store. Reported range, 1000 miles.
    San José, Calif.--Herrold Laboratories station. Range, up to 500 miles.
    Seattle, Wash.--Seattle Post Intelligencer (newspaper). Range, 60 miles.
IN addition to the foregoing stations there are thousands of private and amateur stations scattered throughout every state having ranges up to 50 miles. Stations in Detroit, Mich., Cleveland and Akron, Ohio, and Davenport, Iowa, while less powerful than many of the others mentioned, have transmitting radii great enough in extent to enable thousands of listeners in their vicinity to enjoy the daily news reports and regular evening concerts.

Callsigns and Licence Classifications: Most of the stations listed above which have callsigns starting with K or W (WJZ, WBZ, WQB, KYW, KDKA etc.) held the Limited Commercial licences which, with the adoption of the December 1, 1921 broadcast service regulations, had become mandatory for private broadcasting stations. (Many of these stations had previously held licences in other classifications, especially Experimental and Amateur. Also, it was not uncommon for a station to hold more than one licence, and operate under different callsigns according to the licence classification it fell under at the time it was on the air).

Numerous stations in this list have callsigns that start with a number, which was the Radio Inspection District in which they were located, followed by two or three letters. Despite the similarity of their calls, these stations were actually divided among four different licence classifications, although what they did have in common was that, because of the December 1st regulations, they all were now required to get Limited Commercial licences if they wanted to continue to make broadcasts intended for the general public. Some of the stations reviewed had standard Amateur licences, which meant they normally transmitted on the congested wavelength of 200 meters (1500 kilohertz). The callsign rule for standard Amateur stations was that the letter following the district number could be anything except X, Y, or Z. The only standard Amateur station call appearing in the above list is 4CD in Atlanta, Georgia. The other three licence categories -- Experimental, Technical and Training School, and Special Amateur -- which had callsigns starting with district numbers were known collectively as the Special Land stations. These stations generally were allowed to transmit on the less congested wavelengths between 600 and 200 meters (500 to 1500 kilohertz). Experimental stations had callsigns with an X as the first letter following the district number. Some of the more prominent Experimental stations from this list include 1XE in Medford Hillside, Massachusetts, 8XB in Cincinnati, Ohio, and 9XAD in Kansas City, Kansas. Technical and Training School licences were most commonly issued to colleges and universities, and their callsigns had a Y immediately after the district number. One Technical and Training School station is included in this list -- 9YY, Lincoln, Nebraska (University of Nebraska). Finally, Special Amateur licences allowed qualified amateurs to legally operate on the less congested wavelengths, and their calls had a Z after the district number. The two Special Amateur stations in this list are 5ZU in Austin, Texas and 9ZAF in Denver, Colorado.

One Government station is also listed. (Government stations were exempt from the private station requirement that broadcast stations have Limited Commercial licences). Stations operated by the U.S. Navy were assigned calls starting with N, including NAA in Arlington, Virginia.

Additional Information: The various land station licence classifications are defined in the August 15, 1919 edition of Radio Communication Laws of the United States, beginning with regulation 51. For a detailed review of U.S. callsign practices, see United States Callsign Policies. For a comprehensive overview of the establishment of the Limited Commercial broadcast service and the current status of many of the stations listed above, see United States Pioneer Broadcast Service Stations. And for more information on radio station lists, see Early Radio Station Lists Issued by the U.S. Government.