Tanning is the art of processing leather goods. The small tanning industry developed on Lesvos in the end of the 19th century using as raw materials leather and hides, locally procured or imported from other regions in Greece, South America or Africa. The greatest tanning factories in Lesvos were in Mytilini, in the Tambakika location in the North Ports, in Plomari and Perama in the Gera vicinity, where one of the biggest tanneries in the Balkan region was built in the end of the 19th century. The tanneries were always built close to the shore so they could easily get water and salt that were indispensable for leather processing. In 1913 twenty major tanneries were in operation throughout Lesvos, reduced to 14 by 1921. This diminishing course continued in the post-WWII years until 1990, the year the last tannery ceased operation in Perama of Gera.