Sønderjyllands Amt
Sønderborg County () is a former province in Denmark, located on the island of Als and the easternmost part of Southern Jutland. Sønderborg County was established in 1920 following the reunification of Denmark and South Jutland following the Schleswig Plebiscites. It was dissolved in 1970 when it merged with three other counties to form South Jutland County. Sønderborg County corresponded geographically to the former Prussian Kreis Sonderburg.