Was looking at old photograph taken circa early 1880s of the same area where Johannesburg now stands and there's obsoletely nothing beyond plant life there (unlike even nearby Pretoria the local Sotho-Tswana peoples didn't have any settlements in present-day Johannesburg prior to the gold mining) and then a photograph taken circa late 1880 and it like million tents are there (maybe that's an exaggeration). Made me wonder about the last "overnight city" was founded in recent history?
This is a fascinating question!
It's true that the "boom town" phenomena occurs in the case of gold rushes - like California in 1849, West Australia in 1851, the Klondike in 1896 - or the construction of railroads or highways or the development of new factory towns or the like.
I would say that the most recent example of this phenomenon is the "new cities" built in China as speculative real estate developments premised around the need for affordable housing for manufacturing workforces, especially during the 2005-2011 housing bubble. In some years, these developments hit big and you get brand-new megacities out of nowhere.
In the past couple of years, with the slowdown in the Chinese economy and particular problems in the real estate sector, the fascinating phenomena of "ghost cities" (originally observed in 2006) where there are massive empty developments in various stages of construction just lying vacant has become more prominent, as developers run out of money or credit, or find it hard to attract industry and residents in a time of COVID lockdowns and the relative decline of Chinese manufacturing as a basis for urbanization.
