Sichuan
From 1955 until 1997 Sichuan had been China's most populous province, hitting 100 million mark shortly after the 1982 census figure of 99,730,000. This changed in 1997 when the Sub-provincial city of Chongqing as well as the three surrounding prefectures of Fuling, Wanxian, and Qianjiang were split off into the new Chongqing Municipality. The new municipality was formed to spearhead China's effort to economically develop its western provinces, as well as to coordinate the resettlement of residents from the reservoir areas of the Three Gorges Dam project.

Q: What Chinese Province had the largest population until 1997?
Sichuan