Starting in 1849 many of the ship crews jumped ship and headed for the gold fields when they reached port. Soon San Francisco Bay had many hundreds of abandoned ships anchored off shore. The better ships were re-crewed and put back in the shipping and passenger business. Others were bought cheap and hauled up on the mud flats and used as store ships, saloons, temporary stores, floating warehouses, homes and a number of other uses. Many of these re-purposed ships were partially destroyed in one of San Francisco's many fires and ended up as landfill to expand the available land. The population of San Francisco exploded from about 200 in 1846 to 36,000 in the 1852 California Census. Unfortunately, the 1850 U.S. Census of San Francisco was burned in one of its frequent fires.