The district was created in 1816 when the area became property of Prussia. After World War I the Saar area was under special government of the League of Nations, which split the district into two. The area around Wadern stayed Prussian, while the Merzig area became part of the Saar area. In 1935, the Saar area rejoined Germany; however, it took till after the World War II that the two parts of the district were reunited in 1946.
The coat of arms show the symbols of those countries which had possessions in the district's area. The top-left show the cross of Trier, the top-right those of Lorraine. The wolfs-hook in the bottom-left represents Dagstuhl, which owned Wadern; the lion in the bottom-right stands for Luxembourg, which owned the western part of the district.