Yesterday the upgrade of Om Noi town (เทศบาลเมืองอ้อมน้อย), Samut Sakhon province, to a city municipality (เทศบาลนครอ้อมน้อย) was announced in the Royal Gazette, making it the 27th city of Thailand. Same as the municipal announcements last week, this change isn't yet covered by the board meeting transcripts available online, thus was decided after mid-September. The announcement was signed on November 11, which I guess is also the date when the change is effective.
Sadly the announcement PDF does not include the map of the municipality - which is not only included in announcements on area changes, but also when the status is changed without any change of area. Without that map, I only relied on the website of Om Noi which only had a small sketch map, thus it took me some time to find their office in Google Earth.
Om Noi was originally a sanitary district, created in 1967 [Gazette]. In 1994 it was upgraded to a subdistrict municipality [Gazette], and in 2002 to a town municipality [Gazette]. While the sanitary district only covered part of the subdistrict Om Noi, apparently with the upgrade to a municipality the area was enlarged to cover the whole subdistrict.