Up until the subdistrict (Tambon) creation ceased in 1997, in a normal year around 100 new subdistricts were established, a number which slowly decreased when going further into the past. But the year 1947 was a very special one with respect of the subdistricts, as a total of 881 subdistricts were created then in only 11 Royal Gazette announcements. Especially one was very lengthy containing 674 of these on 320 pages (Gazette).
I have come across several interesting and noteworthy details while working through all these, but since it would become a very lengthy posting to write down all at once I will only give the overview and a bit of statistics now and will write some further postings on these creations later. It took me more than a month to process them all.
One thing which I am rather sure about already is the fact that these 881 Tambon were not all created in 1941. In a few cases I had to check with ThaiTambon.com to check for the history of the subdistrict, and when it had the creation year cited there it was up to several years earlier. One case I already wrote about where the new subdistricts already got mentioned in a Gazette announcement in 1943. Another indication of this assumption is the fact that there were almost no subdistrict creations in the time before - only one in both 1940 and 1941, one in 1939, two in 1938, and four in 1936. And these are in fact the only announcements of subdistricts creations before 1947 I have found so far.
In median, the subdistricts were created with 6 villages. I already mentioned the six subdistricts which were created with a single village, and the maximum number of villages of 18 occured three times. The province with most new subdistricts announced in 1947 is Phra Nakhon Si Ayutthaya, a total of 58 subdistricts. As the province today has 209 subdistricts, this means 25% of the modern day subdistricts were announced in 1947.