 In San Francisco, many people were initially housed in wooden houses, ships hauled up on the mud flats to serve as homes or businesses, wood-framed canvas tents used for saloons, hotels and boarding houses as well as other flammable structures.All these canvas and wood structures, combined with a lot of drunken gamblers and miners, led almost inevitably to many fires.Most of San Francisco burned down six times in six "Great Fires" between 1849 and 1852.