The Weimar Republic was a federal state, consisting by the end of its existence of 17 "Free States" with their own autonomous governments and regional parliaments - Landtags. The largest parties had a nationwide character. In some Free States, there were local parties, but they did not have a significant influence on imperial politics.

An exception was Bavaria, which was the second most important German state after Prussia. 

The Kaiserreich was a loose federative structure in which individual German monarchies retained their own armies, tax sovereignty, and legal systems. Moreover, Bavaria even maintained a separate foreign ministry.

Under the empire, in most Bavarian districts, candidates from the Catholic Center Party won elections to the Reichstag. In the 1870s, the autonomous Bavarian government, similar to Otto von Bismarck's government in Prussia, conducted a "Kulturkampf" - restricting the rights of the Catholic Church. Priests were forbidden to conduct political propaganda, church appointments were now dependent on state officials, the Church was ousted from the sphere of education, civil marriages were introduced, and the Jesuit order was banned. Under the pressure of repression, confessional solidarity united followers of the Roman Church throughout Germany.

The revolution of 1918-1919 threatened the federal character of the German state, as there were strong sentiments within the ruling "Weimar Coalition" in favor of greater centralization and unification of the Reich. As a result, the imperial government was able to strip the states of their military, tax, and diplomatic sovereignty. Nevertheless, the regions retained domestic political autonomy with their own governments, parliaments, and laws. However, to many Bavarians, even this autonomy seemed insufficient.

In the elections to the Constituent Assembly in January 1919, Bavarian Catholics still acted in a single bloc with the all-German Center Party. However, by 1920 they had finally separated into a distinct Bavarian People's Party (BVP), which defended the principle of federalism. Dominating Bavarian politics, the BVP also participated in national parliamentary elections, consistently gaining 3-4% of the votes. 

Like the Center, the BVP, thanks to its centrist position, could maneuver between the left and the right. In 1919-1920, the party was part of the Bavarian "Weimar Coalition" along with the Social Democrats and left-wing liberals. However, in March 1920, the coalition government was overthrown as a result of a right-wing coup, and the anti-republican right-conservative wing of the BVP, led by Gustav von Kahr, came to power. Until 1924, Kahr clashed with the central authorities in Berlin, seeking to expand Bavarian autonomy and maneuvering on the brink of open separatism. After 1924, the BVP became a more moderate party, which nevertheless continued to cooperate with right-liberal and conservative forces.

As a result, representatives of the BVP headed the Bavarian government throughout almost the entire Weimar period from 1920 to 1933. From 1925 to 1932, the party was even represented in the imperial cabinets of ministers.

The party's choice proved to be fateful during the presidential elections of 1925. In the first round, the BVP nominated its own leader Heinrich Held, who received almost 4% of the votes. In the second round, the republican parties rallied around the Center's candidate Wilhelm Marx. However, the Catholic BVP preferred to support the Protestant candidate from the right - the Kaiserreich's Field Marshal Paul von Hindenburg. In the second round, the gap between Marx and Hindenburg was only 3% in favor of the latter - 45% and 48% respectively. In fact, the BVP ensured Hindenburg's election, who a few years later led the dismantling of the republican regime and handed power to the Nazis.

During the Great Depression, the BVP retained its peasant Catholic electoral base intact. The Nazis grew at the expense of urban liberals and conservatives, as well as rural secular voters.

However, Bavaria could not oppose the Nazis' rise to power. In March 1933, the Bavarian government was overthrown, and Bavarian Reichstag deputies voted to grant Hitler's cabinet emergency powers to issue laws bypassing parliament. In April, the party composition of the Landtag was reformatted in favor of the Nazis, and in July the BVP was forced to dissolve itself.

The "Third Reich" formally retained the German states with their own Nazi governments, but in fact completely destroyed their autonomy - regional parliaments were abolished, and all orders henceforth came from Berlin.

After the collapse of Nazism in 1945, two regional parties were immediately created in Bavaria - the Christian Social Union (CSU) and the Bavarian Party. The CSU was more clerical and oriented towards interaction with the nationwide Christian Democratic Union (CDU). The Bavarian Party was more secular and federalist, balancing on the brink of separatism.

Until the late 1950s, there was a fierce struggle between the two parties for the "bourgeois" Bavarian voter. The winner was the CSU, which since 1946 and to this day (with a brief interruption from 1954 to 1957) continues to lead all Bavarian governments. The Bavarian Party was represented in the first Bundestag, and until the mid-1960s was elected to the Bavarian Landtag. After that, its electoral base was completely absorbed by the CSU, and the party continued its activities exclusively at the municipal level.