It superseded three former administrative regions Alsace, Champagne-Ardenne, and Lorraine on 1 January 2016, as a result of territorial reform which was passed by the French legislature in 2014. Alsace-Champagne-Ardenne-Lorraine was a provisional name, created by hyphenating the merged regions in alphabetical order; its regional council had to approve a new name for the region by 1 July 2016.
Grand Est is the result of territorial reform legislation passed in 2014 by the French Parliament to reduce the number of regions in the part of France in continental Europe from 22 to 13. ACAL is the merger of three regions: Alsace, Champagne-Ardenne, and Lorraine.
The merger has been strongly opposed in Alsace. The territorial reform law allows new regions to choose the seat of the regional councils, but specifically made Strasbourg the seat of the Grand Est regional council, a move to appease the region's politicians.