As such, during the late Qing reforms, mahjong became considered a social issue. Mahjong started to become outlawed indirectly as gambling and smoking opium became criminalized. The ban was not very successful, however, at least until the Chinese cultural revolution.
Why are American mahjong sets the most expensive? American mahjong sets have 166 tiles (Chinese sets only have 144) and include a set of racks to hold the tiles. More tiles, the addition of racks, and a larger box makes the entire set more expensive.