Outside the customs union (Zollverein), the imports being principally coals, bricks and timber, and the exports fish.
In the old Prussian provinces alone there were fifty-three different customs frontiers, and German manufactures could not develop until the growth of the Zollverein brought with it commercial consolidation, internal freedom and greater homogeneity of economic conditions.
In 1866 Hamburg joined the North German Confederation, and in 1871, while remaining outside the Zollverein, became a constituent state of the German empire.
The jurisdiction of the Free Port was on the 1st of January 1882 restricted to the city and port by the extension of the Zollverein to the lower Elbe, and in 1888 the whole of the state of Hamburg, with the exception of the so-called "Free Harbour" (which comprises the port proper and some large warehouses, set apart for goods in bond), was taken into the Zollverein.
Delbriick in 1851 induced Hanover, Oldenburg and SchaumburgLippe to join the Zollverein; and the southern states, which had agreed to admit Austria to the union, found themselves forced in 1853 to renew the old union, from which Austria was excluded.