The early 20th century saw the state of South Dakota fall in with national trends. When World War I began, South Dakota created a State Council of Defense that encouraged increases in food production and set quotas for fundraising for the war effort, primarily through the sale of war bonds. South Dakota did quite well in both regards, far exceeding food production requests and fundraising quotas.
The 1920s and 1930s brought economic disaster to South Dakota, particularly to the east. In the early 1920s, income from farming decreased significantly, and as a result, farm properties lost value. Farmers were unable to service their debts. Bank failures were not uncommon by 1923, and when the stock market crashed in 1929, South Dakota was already reeling.
The Great Depression of the 1930s was not the only disaster to strike the Dakotas at the time. Grasshoppers, drought, severe winter weather, and crop failures added to the already impossible circumstances of farmers. Over 30,000 farm foreclosures occurred in the 1920s and early ’30s. The population of the state declined more than 7 percent as people abandoned their property. Workers in the Black Hills , tied more to mining than agriculture, particularly in Deadwood  and Lead , saw shorter hours, but miners were still working and rode through the Great Depression relatively unscathed.
Implemented in the early 1930s, the New Deal farm legislation brought relief in the form of government subsidies and rewards for low production in order to raise prices. It also brought some interesting projects to life. The Works Progress Administration put over 3.5 million Americans back to work. One of the projects administered by the WPA was the Federal Writers’ Project, which employed over 6,500 people to write about the geography, history, and culture of each state. The WPA guide to South Dakota is still in print today.
The Civilian Conservation Corps, another New Deal project, was also active in South Dakota. There were over 26,000 South Dakotans who worked in the camps at one time or another. The majority were put to work on projects in the Black Hill]. Some of the major projects of the camps included the fire towers at the top of Harney Peak  and Mount Coolidge, and Dinosaur Park in Rapid City . The original buildings used to house the actors and staff of the Black Hills Playhouse in Custer State Park  were originally a CCC camp. At the end of the Great Depression, the need for the CCC no longer existed and the program was discontinued in 1942.
World War II had long-term effects on South Dakota. Deadwood  and Lead  suffered during the war, when the Homestake Mine  was ordered to stop producing gold while the war was on. Many of the miners left to work in the copper mines or to join the armed forces and populations shrunk in these towns. After the war, however, mining techniques were upgraded and gold mining resumed. Several military installations created in the state remained as permanent bases after the war was over. In the Black Hills  area, Ellsworth Air Base in Rapid City  and the Black Hills Ordnance Depot in Igloo, located south of the town of Edgemont, brought increases in population and employment.
National trends in the 1950s and 1960s affected South Dakota and its rural and urban communities. The search for hydroelectric power brought four large dams to the Missouri River in the 1950s, and provided much work for South Dakotans. However, the dams swallowed 500,000 acres of land, about half of which was owned by the Native American tribes located on the Missouri, and once again, reparations were minor.
In the 1960s, the heightening Cold War kept Ellsworth Air Force Base in Rapid City fully occupied as over 150 Intercontinental missile silos were installed and managed by base personnel. The 1960s also brought two interstate highways to the state, one of which, I-90, was of major import to the Black Hill] region, connecting as it did the more populous eastern cities, including those in Nebraska and Minnesota, to the Black Hill]. With the increase in automobile travel and truck freighting, however, the importance of the railroad for passenger travel disappeared. By the late 1960s, there were no longer any passenger rail cars traveling to South Dakota.
The early 1970s brought an air of discontent and the creation of many social organizations, many of them militant, to the United States. The Students for a Democratic Society, the Black Panthers, and the American Indian Movement all were known to use violent means to bring awareness to social issues of the day. In 1973, the American Indian Movement came to South Dakota. In February 1973, members of AIM took over the community of Wounded Knee, protesting corrupt government. FBI agents were sent to remove the AIM occupiers and a siege ensued. For 71 days, AIM held the community; two people were killed, 12 were wounded, and 1,200 were arrested. The event attracted worldwide attention to the plight of Native Americans in the United States. A subsequent trial of AIM leadership relating to the events at Wounded Knee resulted in the acquittal of all charges of wrongdoing.
For over 100 years, the Sioux argued that the 1877 act ratified by Congress was an illegal act, breaking the 1868 Treaty of Fort Laramie, and that the Black Hills  should be returned to the Lakota. The Sioux filed a lawsuit in 1920, the soonest this avenue was open to them, claiming that the Black Hill] were taken without just compensation and triggering a legal battle that continues, on the strength of continuous appeals, to this day. In July 1980, however, a small victory was handed to the Oglala Lakota. The Supreme Court of the United States ruled as follows:
In sum, we conclude that the legal analysis and factual findings of the Court of Claims fully support its conclusion that the terms of the 1877 Act did not effect “a mere change in the form of investment of Indian tribal property.”…Rather, the 1877 Act effected a taking of tribal property, property which had been set aside for the exclusive occupation of the Sioux by the Fort Laramie Treaty of 1868. That taking implied an obligation on the part of the Government to make just compensation to the Sioux Nation, and that obligation, including an award of interest, must now, at last, be paid.
The amount due was to be $17.1 million plus interest from 1877. The money has never been collected, as the Sioux believe the Black Hill] should be returned to them. This decision has been appealed and the lawsuits continue today.
In 1930 the state of South Dakota had a population of about 690,000. The Great Depression, the droughts, and the grasshoppers that attacked the state between 1930 and 1940 reduced the population of the state by 50,000 people. It wasn’t until 1990 that the state population regained its 1930 numbers. Today, the state of South Dakota has a population of approximately 804,000 people, 27 percent of whom live in either Sioux Falls or Rapid City .
While the state continues to increase in population, the increase is primarily in the urban areas. Rural counties are getting older and young people are leaving the state. A conservative state, South Dakota has voted Republican in the last 11 presidential elections. However, this does not make the state predictable on all conservative issues. In the decade ended in 2009, voters twice rejected attempts to make abortion illegal in the state, and passed legislation to ban smoking in all public establishments including casinos and bars. (The latter legislation is being challenged.) It is a state where conservatives are independent and unpredictable.
In order to attract more financial institutions to the state, the legislature removed restrictions on interest rates and successfully lured many credit card companies to Sioux Falls, making financial services an important part of the state’s gross domestic product. Still, the state’s economy remains entwined with the industries of its past: agriculture, ranching, mining, government services, and tourism.