In San Francisco initially many people were 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. Lighting and heat were provided by burning oil lamps or open fires. All these canvas and wood structures housing fires, lanterns and candles 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.