The Zollverein or German Customs Union is a coalition of German states formed to manage tariffs and economic policies within their territories.

Organized by the 1833 Zollverein treaties, the Zollverein formally comes into existence on January 1, 1834. However, its foundations have been in development from 1818 with the creation of a variety of custom unions among the German states.

By 1866, the Zollverein includes most of the German states.

The foundation of the Zollverein is the first instance in history in which independent states had consummated a full economic union without the simultaneous creation of a political federation or union.

Prussia is the prime motivating force behind the creation of the customs union.

Austria is excluded from the Zollverein because of its highly protected industry and also because Prince von Metternich is against the idea.

With the founding of the North German Confederation in 1867, the Zollverein includes approximately 425,000 square kilometers, and has produced economic agreements with several non-German states, including Sweden-Norway.

After the founding of the German Empire in 1871, the Empire assumes the control of the customs union.

However, not all states within the Empire are part of the Zollverein until 1888.

Conversely, Luxembourg, although it is not a state in the German Reich, remains in the Zollverein until 1919.