<P> Public segregation was challenged by individual citizens on rare occasions but had minimal impact on civil rights issues, until December, 1955, in Montgomery, Alabama, Rosa Parks refused to be moved to the back of a bus for a white passenger . Parks' civil disobedience had the effect of sparking the Montgomery Bus Boycott . Parks' act of defiance became an important symbol of the modern Civil Rights Movement and Parks became an international icon of resistance to racial segregation . </P> <P> Segregation was also pervasive in housing . State constitutions (for example, that of California) had clauses giving local jurisdictions the right to regulate where members of certain races could live . In 1917, the Supreme Court in the case of Buchanan v. Warley declared municipal resident segregation ordinances unconstitutional . In response, whites resorted to the restrictive covenant, a formal deed restriction binding white property owners in a given neighborhood not to sell to blacks . Whites who broke these agreements could be sued by "damaged" neighbors . In the 1948 case of Shelley v. Kraemer, the U.S. Supreme Court finally ruled that such covenants were unenforceable in a court of law . However, residential segregation patterns had already become established in most American cities, and have often persisted up to the present (see white flight and Redlining). </P> <P> In most cities, the only way blacks could relieve the pressure of crowding that resulted from increasing migration was to expand residential borders into surrounding previously white neighborhoods, a process that often resulted in harassment and attacks by white residents whose intolerant attitudes were intensified by fears that black neighbors would cause property values to decline . Moreover, the increased presence of African Americans in cities, North and South, as well as their competition with whites for housing, jobs, and political influence sparked a series of race riots . In 1898 white citizens of Wilmington, North Carolina, resenting African Americans' involvement in local government and incensed by an editorial in an African - American newspaper accusing white women of loose sexual behavior, rioted and killed dozens of blacks . In the fury's wake, white supremacists overthrew the city government, expelling black and white office holders, and instituted restrictions to prevent blacks from voting . In Atlanta in 1906, newspaper accounts alleging attacks by black men on white women provoked an outburst of shooting and killing that left twelve blacks dead and seventy injured . An influx of unskilled black strikebreakers into East St Louis, Illinois, heightened racial tensions in 1917 . Rumors that blacks were arming themselves for an attack on whites resulted in numerous attacks by white mobs on black neighborhoods . On July 1, blacks fired back at a car whose occupants they believed had shot into their homes and mistakenly killed two policemen riding in a car . The next day, a full scaled riot erupted which ended only after nine whites and thirty - nine blacks had been killed and over three hundred buildings were destroyed . </P> <P> With the migration to the North of many black workers at the turn of the 20th century, and the friction that occurred between white and black workers during this time, segregation was and continues to be a phenomenon in northern cities as well as in the South . Whites generally allocate tenements as housing to the poorest blacks . It would be well to remember, though, that while racism had to be legislated out of the South, many in the North, including Quakers and others who ran the Underground Railroad, were ideologically opposed to Southerners' treatment of blacks . By the same token, many white Southerners have a claim to closer relationships with blacks than wealthy northern whites, regardless of the latter's stated political persuasion . </P>

The most important changes in civil rights in united states in the 1950s were instituted by