New Zealand

It will be 37 years to the day since the New Zealand radio station, now 1368AM [Village Radio], call sign Station 1XT, first commenced broadcasting from the village in 17th Avenue West. That occasion was to mark the city of Tauranga celebrating its 21st birthday.
On Tuesday April 13, the radio station will be “firing up” its original transmitter, says Station Manager George Stewart.
The 84 year old Collins one kilowatt transmitter was built at Cedar Rapids, Iowa, in the USA.
More about the story sunlive.co.nz
Mike Terry to WRTH fb group (2021-04-11)

United States

What Mediumwave DX sounded like in 1933: this video posted by the Antique Wireless Association features clips recorded by a UK DXer that year of mediumwave stations from the U.S. as received at his location. He was recording to aluminum disc, a process that involved “embossing” rather than cutting, as with lacquer discs. The audio (and reception) quality is pretty amazing: 
https://www.youtube.com/watch?v=R8YrRs5nWeQ.
Andy Robins, Kalamazoo, Michigan USA to WOR groups.io (2021-03-13)

More about this with same link:
http://www.southgatearc.org/news/2021/march/dxing-in-england-1933.htm
James Niven, Austin TX, nrc-am gg via WOR groups.io (2021-03-13)

United States

WLW-AM Begins 100th Year On Air.
It wasn’t Cincinnati’s first radio station, but WLW-AM [700 kHz] is still the biggest.
Cincinnati industrialist Powel Crosley, Jr. began broadcasting WLW-AM over a 20-watt station from his College Hill home on March 2, 1922 – which means that the station is entering its 100th year today.
https://www.wvxu.org/post/wlw-am-begins-100th-year-air?fbclid=IwAR3XY7x_5gCJUeBaMwjqL3P4UebXkP8WvR5HNE1XELPRBqmQsoU1xaxqiPQ#stream/0
IRCA fb group (2021-03-09)

Argentina & Finland

Radio in Argentina
Argentina was a world pioneer in broadcasting, being the third country in the world to make its first regular broadcasts in 1920, having been the first Spanish-speaking country in Latin America to offer daily radio broadcasts. The main stations were in Buenos Aires and Córdoba.
In 1921, the transmission of classical music became a daily occurrence. The following year, the assumption of President Marcelo Torcuato de Alvear was broadcast live.
Also at that time the first advertisements, called “reclames”, were put on the air. At the end of the decade the radio drama was born.
The introduction of the loudspeakers substantially modified the listening conditions. The receiving apparatus was gaining an important place in the home, gathering around the family. Meanwhile, the multiplication of the stations generated the first conflicts over the airwaves, which led to the first regulations on emission frequencies at the end of the 20s.

Finland 1921
Finnish Amateur Radio League is a national non-profit organization for amateur radio enthusiasts in Finland was founded in 1921 and has today approximately 5,000 members.
Finnish Radio Association, Finlands Radioförening was a private association founded in Helsinki in 1923 to promote only the interests of radio listeners. The association also passed listening permits to its members.
The organization had about ten local member associations of radiohobbyists around the country. Each local association also owned its own small radio station to serve so-called close listening. The first actual broadcasting station of this organization started operating in Finland in 1923 in Tampere.
Incidentally, nearly all tube radio listeners were already familiar with most European radio stations at that time. Ylisradio was later established in 1926 by merging all those small radio stations into the same broadcasting company whose 1st own powerful Lahti longwave station began broadcasting in 1928.
Kari Kallio (2021-03-05)

Lithuania

On Sunday evening (24 January 2021), it was announced that Rimantas Pleikys  (1958-2021), a journalist, political figure and founder of several radio stations, had died at the age of 64. He was the founder of M-1 (*1989), Radio Centras (*1990) and Radio Baltic Waves International (*2000). It was during his tenure as member of the Lithuanian parliament that he proposed a Radio Free Belarus, modelled after Radio Free Europe. The public response was unexpectedly negative, because the public did not want a deterioration of relations with the Eastern neighbour. Under a new name his project is still on the air on 1386 kHz with relays in Russian for RFE/RL and NHK World Radio Japan and in several languages for Polskie Radio.  Rimantas Pleikys was also instrumental in saving the short wave station at Sitkunai by a new 100 kW short wave transmitter and a new curtain array. The new facility ended broadcasting in 2017.
Obituaries can be found at
https://www.15min.lt/naujiena/aktualu/lietuva/premjere-reiskia-uzuojauta-del-zurnalisto-politiko-rimanto-pleikio-mirties-56-1444738
The google translation into English seems to reproduce the original fairly well.
Dr Hansjoerg Biener (2021-01-26)

Australia

4BU 1332AM celebrating its 85th birthday.
4BU is an Australian radio station serving the Bundaberg region in Queensland, Australia.
More to the story here.
Mike Terry in WRTH fb group (2020-12-27)

United States

KDKA Pittsburgh Celebrates a Century of Broadcasting.
KDKA Pittsburgh [nowaday 1020 kHz] began regular broadcasting 100 years ago today when the station began an election night broadcast at 6 p.m. on Tuesday, Nov. 2, 1920, from a tiny shack atop one of the Westinghouse Electric buildings in East Pittsburgh.
Four men manned that first broadcast: Engineer William Thomas; telephone line operator John Frazier; R.S. McClelland, a standby; and Leo Rosenberg, radio’s first announcer.
The election returns of the Harding-Cox presidential race were relayed to about 1,000 listeners who learned through this incredible new medium who the next president of the United States would be. (Spoiler Alert: Warren Harding beat James Cox.)
Steve Millam in MWDX – The National Radio Club fb group (2020-11-02)

United States

KDKA Centennial -The birth of Commercial Radio.
November 2, 2020 marks the centennial of radio station KDKA going on the air for the first time. Their first broadcast, considered by many to be the birth of commercial broadcast radio, was to report the election results of the Harding-Cox presidential race. KDKA has been on the air continuously ever since.
To celebrate this historic milestone, Pittsburgh area amateur radio operators, also known as hams, will take to the airwaves with a series of special event stations. Their goal is to contact as many other ham radio operators across the United States and around the world. They will be celebrating the centennial of KDKA for the entire month of November.
KDKA originally began operations in 1916 as an amateur radio station, call sign 8XK, operated by Dr. Frank Conrad, Assistant Chief Engineer of Westinghouse Electric and Manufacturing Company. During World War I, amateur radio operations were ordered to be suspended because of national security concerns. After the war, the operators reorganized the station as a commercial AM radio station. The first transmissions of KDKA were from a makeshift studio on a roof of the Westinghouse K Building in East Pittsburgh.
http://www.southgatearc.org/news/2020/october/kdka-centennial-the-birth-of-commercial-radio.htm#.X5V0voj0mM8
Southgate Amateur Radio News (2020-10-25)

United States

Radio Broadcasting became a reality: Nov. 2, 1920.
By the end of the 20th century’s second decade, three key elements were in place to fuel radio broadcasting: resonant circuitry, a practical means for generating a carrier wave, and methodology for impressing speech and music on that carrier.
These waited only for someone to combine them in an effective way.
A number of individuals — most notably Reginald Fessenden, Lee de Forest and Charles Herrold — had made varying attempts at broadcasting. None took root.
There was little effort to stimulate interest among the public. Early transmissions of speech and music were directed to radio amateurs. There also was little or no notification of how to “listen in.” Nor were there regular operating schedules, nor readily available receivers for the general public. Radio sets were marketed to commercial enterprises, the military and radio amateurs.
[….]
This stemmed from the government’s decision not to allow foreign corporations such as Marconi to exert a virtual monopoly in this area of radio, as had been the case before the war. While that chapter in radio history is too involved to relate in detail here, it resulted in the creation of the Radio Corporation of America.
RCA, along with General Electric, a large player in radio communications, wound up controlling most of the valuable radio patents.
Westinghouse attempted to enter into international radio communications, joining with the International Radio Telegraph Co., successor to Reginald Fessenden’s National Electric Signaling Company, in an attempt to secure a place in this field. The initiative failed due to postwar agreements in place by others including Marconi, Telefunken, and RCA, the new kid on the block.
[….]
Radio World NewsBytes (2020-10-07)