|Data for 1910|
- The Grand Duchy of Saxe-Weimar-Eisenach, officially the Grand Duchy of Saxony (Großherzogtum Sachsen) from 1903
- The duchies of Saxe-Altenburg, Saxe-Coburg and Gotha and Saxe-Meiningen (Herzogtum Sachsen-Altenburg, Herzogtum Sachsen-Coburg und Gotha, Herzogtum Sachsen-Meiningen)
- The principalities of Reuss Elder Line (Fürstentum Reuß Ältere Linie), Reuss Younger Line (Fürstentum Reuß Jüngere Linie), Schwarzburg-Rudolstadt (Fürstentum Schwarzburg-Rudolstadt) and Schwarzburg-Sondershausen (Fürstentum Schwarzburg-Sondershausen)
These lands were bordered to the north and west by Prussian regions, especially the Regierungsbezirk of Erfurt, but also those of Kassel and Merseburg, in places as enclaves. In addition numerous Prussian exclaves were mixed up among the Thuringian states. These were the county (Landkreis) of Schleusingen and town of Suhl, the county of Herrschaft Schmalkalden and Barchfeld, the region around Wandersleben and Mühlberg, the county of Ziegenrück and town of Ranis, and the villages of Kamsdorf, Blankenberg, Sparnberg, Blintendorf and Gefell, which belonged to the county of Ziegenrück but were separated from it. Other Prussian exclaves were the villages of Abtlöbnitz near Camburg and Kischlitz near Eisenberg.
To the east, the Kingdom of Saxony was the neighbouring state, which also had various exclaves. These were Liebschwitz near Gera with the municipalities and lands of Lengefeld, Liebschwitz, Lietzsch, Niebra, Pösneck, and Taubenpreskeln, as well as the neighbouring municipalities of Hilbersdorf, Loitzsch, Rückersdorf, Thonhausen and Grobsdorf. Also worth mentioning are the municipality of Bocka near Altenburg and Kauritz near Meerane.
The Kleinstaaterei was highly valued, but on the territory of the present Free State of Thuringia in the early 20th century there were eight small states (Kleinstaaten), Prussian areas in several provinces (Regierungsbezirken) and several small Saxon exclaves. The fragmentation of the states was made particularly acute because the little states did not form single enclosed territories, but were scattered in a confusing melange. In 1913 there was an exchange of land between Saxe-Weimar-Eisenach and Saxe-Meiningen. The Meiningen village of Lichtenhain outside Jena was exchanged for parts of Kranichfeld that belonged to Weimar. In principle less sensible: it did lead to a tidying up of the boundaries in Kranichfeld, but the Meiningen exclave of Kranichfeld was not removed, but enlarged. Apparently Saxe-Weimar-Eisenach could not or would not offer other land for exchange.
During the period of the German Empire the Thuringian states each had a voice in the Bundesrat - in all eight votes (the duchies of Coburg and Gotha only had a joint vote). They thus formed a significant block, especially when one considers that the Kingdom of Saxony, for example, only had four votes. However the Thuringian states rarely agreed with one another. Until 1903 only five states were represented by the Weimar delegates in the Bundesrat. Saxe-Coburg and Gotha had its own delegate, Saxe-Meiningen was represented by Bavaria and Reuss Elder Line by Mecklenburg-Schwerin.
The Higher Regional Court (Oberlandesgericht) of Jena was, according to the new Imperial Court Constitution Act (Reichsgerichtsverfassungsgesetz) of 1 October 1878 the only institution, that was responsible for all the Thuringian states. Only Schwarzburg-Sondershausen fell under the jurisdiction of the Oberlandesgericht in Naumburg. A second common institution was the University of Jena with the Ernestine duchies as their sponsor states. From 1817 the Duchy of Saxe-Coburg was no longer part of them.
In November 1918 the centuries-long, territorial fragmentation of the Thuringian region came to an end. In the federal states, as in the whole of the German Empire, the republic was declared and the reigning dukes and princes abdicated. The old Thuringian duchies and principalities became free states.
The two free states of Reuss E.L. and Reuss Y.L. merged on 21 December 1918 to form the Republic of Reuss, the union between Saxe-Gotha and Saxe-Coburg was dissolved on 12 April 1919 and they formed their own free states.
The governments of Saxe-Altenburg, Saxe-Coburg and Gotha, Saxe-Gotha, Saxe-Meiningen, Saxe-Weimar-Eisenach, Schwarzburg-Rudolstadt, Schwarzburg-Sondershausen and the Republic of Reuss took part in negotiations about a merger of all Thuringian states, if possible including the Prussian elements. But because Prussia was not prepared for any kind of land exchange, the founding of the state as a so-called "Little Thuringian Solution" was taken forward.
In the course of the foundation discussions the state governments voiced misgivings from Saxe-Meiningen and Coburg as to whether being annexed by the new state would be advantageous for them, because the Franconian-influenced region south of the Rennsteig path had always been more strongly linked to Bavaria, both linguistically and socially. For this reason on 30 November 1919 in Saxe-Coburg a plebiscite was held in which the majority of the people voted against being merged into the state of Thuringia. The misgivings of Saxe-Meiningen were resolved inter alia by a "guarantee of existence" (Bestandsgarantie) for the IHK Sonneberg and for the counties.
The region of the Evangelical-Lutheran Church in Thuringia corresponds, even today, apart from a few small Prussian enclaves, to the boundaries of the State of Thuringia in 1920. Only the exclave of Ostheim, which used to belong to Saxe-Weimar-Eisenach went to the Evangelical-Lutheran Church in Bavaria in 1972, in line with the political situation of the time.
- The Thuringian states (with many individual maps)
- Law concerning the State of Thuringia of 30 April 1920