Local morale was affected for years by the collapse of the Division Street Bridge early in the morning on December 15, 1915, which killed five people and injured over 20, but a new bridge was built (eventually replaced in 1994). The 1920 census showed a net increase of just 35 individuals, which actually indicates that thousands left the city when considering the natural growth rate of a population. Growth in the 1920s and 1930s remained slow but less drastically so, forcing city boosters to market the city as a quiet, comfortable place suitable for raising a family rather than a dynamic community full of opportunity. The Inland Empire was heavily dependent on natural resources and goods produced from mines, forests, and farms, which experienced a fall in demand. The situation improved slightly with the start of World War II as aluminum production commenced in Spokane due to the area's cheap electricity (produced from regional dams) and the increased demand for airplanes.