World War I (1914–18) hastened the end of Mississippi’s physical and psychological isolation, and most of the bitterness remaining from the Civil War was lost in a surge of patriotism. Between World War I and World War II (1939–45) the state was affected by an agricultural depression in the 1920s, the disastrous Mississippi River flood of 1927, and the Great Depression of the 1930s, as well as the coming of farm-production controls and the beginnings of new industrialization. After World War II, government farm programs and mechanization revolutionized agricultural production.

In 1954 the U.S. Supreme Court declared racially segregated schools unconstitutional. That decision was followed by years of legal attacks against racial segregation and by large-scale registration of Southern black voters. In 1955 Emmett Till, a 14-year-old black boy from Chicago, was brutally murdered in Mississippi after allegedly whistling at a white woman in a local grocery store, and his white murderers were acquitted of the crime; this event jolted the country and further fueled the movement for civil rights. White Mississippians reacted to black protests, marches, and demonstrations with increasing violence during the early 1960s. In 1962, state officials defied a U.S. Supreme Court ruling that ordered the admission of a black student, James H. Meredith, to the University of Mississippi. Following a night of rioting during which two people were killed, Meredith was admitted and the colour barrier was officially broken in Mississippi. The violence continued, however, with the most serious incident occurring during the “long, hot summer” of 1964, when the Ku Klux Klan murdered three young civil rights workers—two white and one black—and deposited their bodies in a partially finished dam near the town of Philadelphia, Miss.

Mississippi maintained a dual, segregated school system, despite its unconstitutionality, into the late 1960s. Finally, in October 1969, under a federal court order, the state’s school system was unified and desegregated. Although the great majority of white Mississippians opposed the integration of white and black students in the schools, they adjusted to that change with only minor isolated incidents of violence. Over the following decades a succession of strong and progressive governors helped to lead Mississippi from its troubled history as a socially conservative society into a new era of black and white cooperation.

Mississippi since the mid-20th century

After accommodating themselves to the major social changes of the mid-20th century, Mississippians could at last turn their attention and energy to the development of the state’s human and natural resources. By the 1970s, economic development was proceeding at a moderate but steady pace. Out-migration of white Mississippians had virtually ceased, and among the black population it had declined significantly. Although per capita income remained below the national average, it had risen substantially as a result of urbanization, industrialization, and the decline in agricultural employment.

A development that both paralleled and promoted this economic and social progress was the growth of the two-party system. Until the mid-20th century the Democratic Party had held a monopoly on the state’s political process. Since that time, however, the Republican Party has challenged the once dominant party at every level. This development has shifted the focus of the political debate in Mississippi from a defense of old traditions to a discussion of new alternatives. Although the state’s limited natural resources and its long years of agricultural dependency and racial discrimination left a lasting mark, Mississippi by the early 21st century had made notable progress toward overcoming the attitudes and attributes that had impeded its social, economic, and political development for so many years.