Bas-Rhin (; Alsatian: Unterelsàss) is a department in the Alsace-Champagne-Ardenne-Lorraine region of France. The name means "Lower Rhine". It is the more populous and densely populated of the two departments of the traditional Alsace region, with 1,109,460 inhabitants in 2013. The prefecture and the General Council are based in Strasbourg. The INSEE and Post Code is 67.