When did the Punjab Reorganisation Act, 1966 come into effect?
The Punjab Reorganisation Act, 1966 came into effect on October 31, 1966. This can be inferred from the given context where it states "the immediately before The commencement of this Constitution were being administered as if they were Chief Commissioners’ Provinces under the names of Himachal Pradesh and Bilaspur and the territories specified in sub-section (1) of section 5 of the Punjab Reorganisation Act, 1966."