The Mainkreis was one of the 15 districts of the Kingdom of Bavaria between 1806 and 1837 (since 1817 as Obermainkreis). Its name meant in German the “District of the Main” because the Main River ran through it. It was the predecessor of the Regierungsbezirks Oberfranken (Administrative Regional District of Upper Franconia).
In the years between 1806 and 1808 the Kingdom of Bavaria was divided in 15 (state) districts, whose names were taken from their rivers. The Mainkreis, with Bamberg as its capital, was initially composed of 18 rural divisions and, since 1809, of the independent cities of Bamberg and Schweinfurt. In 1810 it grew significantly with the annexation of the Naabkreis. It was again enlarged when it received 12 rural divisions from the former Principality of Bayreuth. The district's headquarters was then moved to Bayreuth. The Mainkreis was renamed in 1817 Obermainkreis [District of the Upper Main River] and slightly expanded. At the same time, a new district was created with the name of Untermainkreis [District of the Lower Main River]. At the request of King Ludwig I, the Territorial Reorganization (Gebietsreform) of 29 November 1837 was made by separating the Oberpfalz (Upper Palatinate) judicial districts from the former Naabkreis and renaming the shrunken Obermainkreis “Oberfranken” [Upper Franconia].
- (de) Handbuch der bayerischen Ämter, Gemeinden und Gerichte 1799 - 1980 (Guide of the Bavarian Districts, Municipalities and Courts 1799 - 1980), written by Richard Bauer, Reinhard Heydenreuter, Gerhard Heyl, Emma Mages, Max Piendl, August Scherl, Bernhard Zittel and edited by Wilhelm Volkert, Senior Professor at the University of Regensburg, Munich, 1983, ISBN 3-406-09669-7