American Civil War, almost four million blacks were enslaved in the South, only white men of property could vote, and the
Naturalization Act of 1790 limited U.S. citizenship to whites only.
 Following the Civil War, three constitutional amendments were passed, including the
13th Amendment (1865) that ended slavery; the
14th Amendment (1868) that gave African-Americans citizenship, adding their total population of four million to the official population of southern states for
Congressional apportionment; and the
15th Amendment (1870) that gave African-American males the right to vote (only males could vote in the U.S. at the time). From 1865 to 1877, the United States underwent a turbulent
Reconstruction Era trying to establish free labor and
civil rights of freedmen in the South after the end of slavery. Many whites resisted the social changes, leading to insurgent movements such as the
Ku Klux Klan, whose members attacked black and white
Republicans to maintain
white supremacy. In 1871, President
Ulysses S. Grant, the U.S. Army, and U.S. Attorney General
Amos T. Akerman, initiated a campaign to repress the KKK under the
 Some states were reluctant to enforce the federal measures of the act; by the early 1870s, other white supremacist and
paramilitary groups arose that violently opposed African-American legal equality and suffrage.
 However, if the states failed to implement the acts, the laws allowed the
Federal Government to get involved.
 Many Republican governors were afraid of sending black militia troops to fight the Klan for fear of war.
disputed election of 1876 resulted in the end of Reconstruction and federal troops were withdrawn, whites in the South regained political control of the region's state legislatures by the end of the century, after having intimidated and violently attacked blacks before and during elections.
From 1890 to 1908, southern states passed new constitutions and laws to
disenfranchise African Americans and many
poor whites by creating barriers to voter registration; voting rolls were dramatically reduced as blacks and poor whites were forced out of electoral politics. While progress was made in some areas, this status of excluding African Americans from the political system lasted in most southern states until national civil rights legislation was passed in the mid-1960s to provide federal enforcement of constitutional voting rights. For more than 60 years, blacks in the South were not able to elect anyone to represent their interests in Congress or local government.
 Since they could not vote, they could not serve on local juries.
During this period, the white-dominated
Democratic Party maintained political control of the South. With whites controlling all the seats representing the total population of the South, they had a powerful voting block in Congress. The
Republican Party—the "party of Lincoln"—which had been the party that most blacks belonged to, shrank to insignificance as black voter registration was suppressed. Until 1965, the "
solid South" was a one-party system under the Democrats. Outside a few areas (usually in remote
Appalachia), the Democratic Party nomination was tantamount to election for state and local office.
 In 1901, President
Theodore Roosevelt invited
Booker T. Washington to dine at the
White House, making him the first African American to attend an official dinner there. "The invitation was roundly criticized by southern politicians and newspapers." Washington persuaded the president to appoint more blacks to federal posts in the South and to try to boost African-American leadership in state Republican organizations. However, this was resisted by both white Democrats and white Republicans as an unwanted federal intrusion into state politics.
During the same time as African Americans were being disenfranchised, white Democrats imposed
racial segregation by law. Violence against blacks increased, with numerous
lynchings through the turn of the century. The system of
de jure state-sanctioned racial discrimination and oppression that emerged from the post-Reconstruction South became known as the "Jim Crow" system. The
United States Supreme Court, made up almost entirely of Northerners, upheld the constitutionality of those state laws that required
racial segregation in public facilities in its 1896 decision
Plessy v. Ferguson, legitimizing them through the "
separate but equal" doctrine.
 Segregation, which began with slavery, continued with Jim Crow laws, with signs used to show blacks where they could legally walk, talk, drink, rest, or eat.
 For those places that were racially mixed, non whites had to wait until all white customers were dealt with.
 Elected in 1912, President
Woodrow Wilson ordered segregration throughout the federal government.
Segregation remained intact into the mid-1950s, when many states began to gradually integrate their schools following the unanimous Supreme Court decision in
Brown v. Board of Education that overturned Plessy v. Ferguson. The early 20th century is a period often referred to as the "
nadir of American race relations". While tensions and
civil rights violations were most intense in the South, social discrimination affected African Americans in other regions as well.
 At the national level, the Southern block controlled important committees in Congress, defeated passage of laws against lynching, and exercised considerable power beyond the number of whites in the South.
Characteristics of the post-Reconstruction period:
Racial segregation. By law, public facilities and government services such as education were divided into separate "white" and "colored" domains.
 Characteristically, those for colored were underfunded and of inferior quality.
Disenfranchisement. When white Democrats regained power, they passed laws that made voter registration more restrictive, essentially forcing black voters off the voting rolls. The number of African-American voters dropped dramatically, and they were no longer able to elect representatives. From 1890 to 1908, Southern states of the former Confederacy created constitutions with provisions that disfranchised tens of thousands of African Americans, and U.S. states such as Alabama disenfranchised poor whites as well.
Exploitation. Increased economic oppression of blacks through the
convict lease system,
Asians, denial of economic opportunities, and widespread employment discrimination.
- Violence. Individual, police, paramilitary, organizational, and
mob racial violence against blacks (and Latinos in the
Southwest and Asians in
KKK night rally in
, c. 1920
African Americans and other ethnic minorities rejected this regime. They resisted it in numerous ways and sought better opportunities through lawsuits, new organizations, political redress, and labor organizing (see the
African-American civil rights movement (1896–1954)). The
National Association for the Advancement of Colored People (NAACP) was founded in 1909. It fought to end race discrimination through
litigation, education, and
lobbying efforts. Its crowning achievement was its legal victory in the Supreme Court decision
Brown v. Board of Education in 1954 when the Court rejected separate white and colored school systems and, by implication, overturned the "
separate but equal" doctrine established in
Plessy v. Ferguson of 1896.
The integration of Southern public libraries involved many of the same characteristics seen in the larger civil rights movement.
 This includes sit-ins, beatings, and white resistance.
 For example, in 1963 in the city of
Anniston, Alabama, two black ministers were brutally beaten for attempting to integrate the public library.
 Though there was resistance and violence, the integration of libraries was generally quicker than integration of other public institutions.
Colored Sailors room in World War I
Black veterans of the military after both World Wars pressed for full civil rights and often led activist movements. In 1948, they gained integration in the military under President
Harry Truman, who issued
Executive Order 9981 to accomplish it. The situation for blacks outside the South was somewhat better (in most states they could vote and have their children educated, though they still faced discrimination in housing and jobs). From 1910 to 1970, African Americans sought better lives by migrating north and west out of the South. Nearly seven million blacks left the South in what was known as the
Great Migration. So many people migrated that the demographics of some previously black-majority states changed to white majority (in combination with other developments). The rapid influx of blacks disturbed the racial balance within Northern cities, exacerbating hostility between both black and white Northerners. The
Red Summer of 1919 was marked by hundreds of deaths and higher casualties across the U.S. as a result of race riots that occurred in more than three dozen cities, such as the
Chicago race riot of 1919 and the
Omaha race riot of 1919. Stereotypic schemas of Southern blacks were used to attribute issues in urban areas, such as crime and disease, to the presence of African-Americans. Overall, African-Americans in Northern cities experienced
systemic discrimination in a plethora of aspects of life. Within employment, economic opportunities for blacks were routed to the lowest-status and restrictive in potential mobility. Within the housing market, stronger discriminatory measures were used in correlation to the influx, resulting in a mix of "targeted violence,
redlining and racial steering".
White tenants seeking to prevent blacks from moving into the
erected this sign,
Housing segregation was a nationwide problem, persistent well outside the South. Although the federal government had become increasingly involved in mortgage lending and development in the 1930s and 1940s, it did not reject the use of race-restrictive covenants until 1950.
 Suburbanization was already connected with
white flight by this time, a situation perpetuated by real estate agents' continuing
discrimination. In particular, from the 1930s to the 1960s the National Association of Real Estate Boards (NAREB) issued guidelines that specified that a realtor "should never be instrumental in introducing to a neighborhood a character or property or occupancy, members of any race or nationality, or any individual whose presence will be clearly detrimental to property values in a neighborhood."
Invigorated by the victory of Brown and frustrated by the lack of immediate practical effect, private citizens increasingly rejected gradualist, legalistic approaches as the primary tool to bring about
desegregation. They were faced with "
massive resistance" in the South by proponents of racial segregation and
voter suppression. In defiance, African-American activists adopted a combined strategy of
nonviolent resistance, and many events described as
civil disobedience, giving rise to the African-American civil rights movement of 1954–1968.