As a result of the Prussian Administrative Reforms of 1867 the Lahn district was created with the county seat of Diez. It Initially belonged to the lower Lahn Limburg circle. The episcopal city became, however, in 1886 the seat of the newly established district of Limburg. In the course of municipal reform in 1969 Loreley circle the lower Lahn (located in St. Goarshausen) Rhein-Lahn-Kreis merged with the spa town of Bad Ems, which became the country seat. Diez was no longer even a regional administrative capital.