Already in the 17th century there were houseboats in Amsterdam. They belonged to foreign traders in glass-and earthenware who sold their merchandise illegally. In the 19th century there were ships all over the city, they were used as housing for the laborers.The wooden barges were replaced by steel barges. In the 1920’s the number of houseboats increased from 85 to over 1100 due to housing shortage. After the Second World War the number increased once more, especially in the sixties and seventies, the Hippie era. Nowadays there are over 2500 houseboats in Amsterdam.