Five days after the Voting Rights Act of 1965 became law, the black neighborhood of Watts in south central Los Angeles, California, erupted in riots. Police brutality and poor living conditions provoked the uprising, which ultimately took 34 lives, destroyed 209 buildings, and led to over 4000 arrests. King visited the city on 17 August, condemning the violence, but emphasizing the validity of its causes. After Selma, and encouraged by Watts, King turned his attention to Northern and Western cities, which suffered a kind of racial tension that his victories in the South had not relieved.
Late in 1965, he and the SCLC chose Chicago as the site for a Northern urban campaign. In February 1966, King rented an apartment in Chicago slums for his family and himself, and began organizing protests against poverty and discrimination in housing and employment. Increasingly his focus was economic: for the Johnson Administration would go no further with federal legislation, and only by securing decent jobs and homes could African Americans escape the kind of conditions that had proven so explosive in Watts.
King planned a massive rally in Chicago for 10 July, 1966, a day he named "Freedom Sunday." Developments in the South, however, took him away from Chicago shortly before the event: in June, a man named James Meredith, who had been the first black student at the University of Mississippi, was shot by whites and seriously wounded while working on a voter-registration drive. The major civil rights organizations–CORE, SNCC, and the SCLC– descended on Mississippi and coordinated a march, called the Meredith March, from the site of the shooting to Jackson, Mississippi.
In Mississippi, however, King sensed divisions within the movement that he had sensed before–indeed, they now seemed to be deepening: members of SNCC considered King's strategies to be decreasingly effective as racial violence increased. This attitude was embodied by Stokely Carmichael, the newly elected head of SNCC, who, during the Meredith March, suggested "Black Power" as a rallying cry for the movement. King and the SCLC refused to endorse the slogan, fearing it would alienate white sympathy. For the time being, King and Carmichael smoothed over their differences, but, in the fall, Carmichael, along with Bobby Seale, founded the Black Panther Party, an overtly militant organization. Schisms widened over a disagreement regarding who would speak at the march's concluding rally.
King returned to Chicago in time for Freedom Sunday, at which he addressed a crowd of 45,000 and nailed a list of grievances to the door of City Hall. King urged the city, specifically Chicago's Mayor Daley, to spend more money on public schools, to integrate them, to build low-rent housing, and to support African-American-run banks. Shortly after Freedom Sunday, black youths rioted on Chicago's West Side, leading to the deployment of the National Guard, and suggesting just how limited was King's influence over events in that city; in general, his Chicago campaign was characterized by meager returns on great investments. Chicago's Operation Breadbasket, led by Jesse Jackson and supported by King, met with only limited success in creating new job opportunities for Chicago blacks. This metropolis of the North resisted tactics that had succeeded in the cities of the South.
In addition to urban economic questions, King turned his attention to the Vietnam War. He had spoken out against the war as early as 1965, but, as it escalated, as it taken an increasingly disproportionate number of young black lives, and as it appeared more and more a war of capitalists against peasants, King became bitterly vocal. On 4 April 1967 at New York's Riverside Church, King delivered his first sermon devoted entirely to the issue of Vietnam. On 15 April he participated in the Spring Mobilization for Peace in New York, an anti-war protest unrelated to the Civil Rights Movement.