Race relations was one area with great potential for violence, although many black leaders stressed nonviolence. Since the mid-1950s, Dr. Martin Luther King and others had been leading disciplined mass protests of black Americans in the South against segregation, emphasizing appeals to the conscience of the white majority. The appeals of these leaders and judicial rulings on the illegality of segregationist practices were vital parts of the Second Reconstruction, which transformed the role and status of black Americans, energizing every other cultural movement as well.

At the same time, southern white resistance to the ending of segregation, with its attendant violence, stimulated a northern-dominated Congress to enact (1957) the first civil rights law since 1875, creating the Commission on Civil Rights and prohibiting interference with the right to vote (blacks were still massively disenfranchised in many southern states). A second enactment (1960) provided federal referees to aid blacks in registering for and voting in federal elections. In 1962, President Kennedy dispatched troops to force the University of Mississippi (a state institution) to admit James Meredith, a black student. At the same time, he forbade racial or religious discrimination in federally financed housing.

Kennedy then asked Congress to enact a law to guarantee equal access to all public accommodations, forbid discrimination in any state program receiving federal aid, and outlaw discrimination in employment and voting. After Kennedy's death, President Johnson prodded Congress into enacting (August 1965) a Voting Rights Act that eliminated all qualifying tests for registration that had as their objective limiting the right to vote to whites. Thereafter, massive voter registration drives in the South sent the proportion of registered blacks spurting upward from less than 30% to over 53% in 1966.

The civil rights phase of the black revolution had reached its legislative and judicial summit. Then, from 1964 to 1968, more than a hundred American cities were swept by race riots, which included dynamitings, guerrilla warfare, and huge conflagrations, as the anger of the northern black community at its relatively low income, high unemployment, and social exclusion exploded. At this violent expression of hopelessness the northern white community drew back rapidly from its reformist stance on the race issue (the so-called white backlash). In 1968, swinging rightward in its politics, the nation chose as president Richard M. Nixon, who was not in favor of using federal power to aid the disadvantaged. Individual advancement, he believed, had to come by individual effort.

Nonetheless, fundamental changes continued in relations between white and black. Although the economic disparity in income did not disappear — indeed, it widened, as unemployment within black ghettos and among black youths remained at a high level in the 1970s — white-dominated American culture opened itself significantly toward black people. Entrance requirements for schools and colleges were changed; hundreds of communities sought to work out equitable arrangements to end de facto segregation in the schools (usually with limited success, and to the accompaniment of a white flight to different school districts); graduate programs searched for black applicants; and integration in jobs and in the professions expanded. Blacks moved into the mainstream of the party system, for the voting-rights enactments transformed national politics. The daily impact of television helped make blacks, seen in shows and commercial advertisements, seem an integral part of a pluralistic nation.

Mexican Americans and Puerto Ricans were also becoming more prominent in American life. Reaching the level of 9 million by the 1960s, Spanish-surnamed Americans had become the second largest ethnic minority; they, too, were asserting their right to equitable treatment in politics, in culture, and in economic affairs.