Before indoor plumbing, families used unsanitary pits or cesspools, then relied on small wooden outhouses or privies that offered privacy and shelter from the elements, while chamber pots served for nighttime emergencies. Early outhouses set over shallow trenches created serious public health problems: when pits filled, families moved the structure to a new trench, and poorly ventilated buildings with dirt floors and gaps in the wallboards allowed flies, mosquitoes, rats, and other rodents to spread germs, while badly dug pits contaminated groundwater and nearby waterways used for drinking water. During the 1930s, Works Progress Administration outhouses introduced concrete foundations and improved ventilation that made them cleaner and more comfortable than earlier models, and older rural outhouses were often reused as small storage sheds when replaced. Through the Works Progress Administration and in cooperation with the Public Health Service, the federal government sought to improve rural living conditions during the Great Depression, constructing more than 2,000,000 sanitary privies across the United States between 1933 and the early 1940s, with families usually paying $15 - $30 for materials while government workers built them. Outhouses often bore a crescent moon or sunburst cut into or above the door, symbols for women and men that also admitted light into the dark interior while avoiding the fire hazard of lanterns or candles.