I have just checked my files and I need to confirm what Ray suggested, that the decision to rotate the AGP between states was made in the thirties, namely April 1939.
The locations for the 1938 and 1939 GPs were made out of necessity after Phillip Island became unsuitable and no venue could be found for 1936. The December 1936 South Australian Grand Prix was retrospectively counted as the "1937 AGP", but then Bathurst became available as a stand alone circuit, and was the only suitable choice for 1938.
In 1939 the Grand Prix was at Lobethal, again simply as an alternative to Bathurst, but NO decision had been made to officially rotate the event at that stage.
But, as a result of the victory by WA driver Alan Tomlinson, Western Australia quickly made application to the Australian Automobile Association to hold the event at Albany in January1940. That application was approved in April 1939, and AT THAT SAME MEETING of the AAA, the following dates were allocated -
Of course war intervened, and the above allocations had to be scrapped. The issue was discussed at the annual meeting of the AAA in Surfers Paradise on the 30th October 1946 where a new allocation of dates was accepted being - 1947 - NSW; 1948 - Victoria; 1949 - QLD; 1950 - South Australia etc
It must be noted that by the beginning of 1949, all involved realized that Queensland was having difficulties finding a suitable location for their '49 AGP, so Victoria pushed hard to be allowed to stage the event again, but their efforts were rebuffed, which led to a virtual boycott of Victorian entrants for the Leyburn race.
Immediately after the war Western Australia made application to hold the first post-war grand prix at Caversham in 1947, on the basis that it had already been decided they were to host the next AGP following South Australia in 1939 (namely 1940).
... but their request was rejected.
It may well be the AAA wanted the most "high profile" venue that would attract the most competitors to help kick-start national motor racing in those difficult post-war years.
Edited by Porsche718, 03 October 2022 - 05:43.