From the time of the Louisiana Purchase and the expedition of Lewis and Clark, Missouri and the nation moved during the 19th century from a rural frontier to an urban industrialized society, and by the early 20th century the need was recognized for public places where citizens could enjoy recreation in a natural setting. In 1917, the Missouri Legislature began creating a state park system by setting aside five percent of hunting and fishing license fees for state parks, following the federal government's establishment of the National Park Service the previous year. Funding problems hindered progress until the share was increased to 25 percent in 1924, when state parks began to be acquired, including Big Spring as the first state park that year, and by 1927 Missouri's park system was the fifth largest in the nation. Missouri's forests, fish, and wildlife had also suffered during the 19th century, and controversy surrounded the use of license fees for state parks and especially historic sites. In 1936, a constitutional amendment separated the state parks and Department of Conservation, leaving the parks without a dedicated source of funding, but New Deal programs during the Great Depression, including the Civilian Conservation Corps, brought federal help. World War II stalled further progress, but after the war increased demand for recreational facilities and the 1945 Constitution, which better defined state parks and mandated funding for the next 15 years, renewed the system's growth. In 1974 the system became part of the new Missouri Department of Natural Resources, and environmental awareness in the 1970s further defined its mission by increasing appreciation for protecting natural and cultural resources. Progress slowed during the economic downturn of the 1980s, but a 1984 sales tax referendum supported by Missouri voters, along with a statewide bond issue and the parks-and-soils sales tax, funded a renaissance of renovation, maintenance, and stewardship, added parks such as Katy Trail State Park, and helped carry the system into the 21st century with continued public support.