Plessy vs. Ferguson
Some sixty-three years before Rosa Parks, on June 7, 1892, a 30-year-old colored shoemaker named Homer Plessy was jailed for sitting in the "White" car of the East Louisiana Railroad. Plessy was only one-eighths black and seven-eighths white, but under Louisiana law, he was considered black and therefore required to sit in the "Colored" car.
One drop of "colored" blood made you "colored."
Plessy went to court and argued, in Homer Adolph Plessy v. The State of Louisiana, that the Separate Car Act violated the Thirteenth and Fourteenth Amendments to the Constitution. He was found guilty of refusing to leave the "white" car.
Homer Plessy appealed to the Supreme Court of Louisiana, which upheld Ferguson's decision. In 1896, the Supreme Court of the United States heard Plessy's case and found him guilty once again.
The lone dissenter, Justice John Harlan, showed incredible foresight when he wrote "Our Constitution is color-blind, and neither knows nor tolerates classes among citizens. In respect of civil rights, all citizens are equal before the law...In my opinion, the judgment this day rendered will, in time, prove to be quite as pernicious as the decision made by this tribunal in the Dred Scott case...The present decision, it may well be apprehended, will not only stimulate aggressions, more or less brutal and irritating, upon the admitted rights of colored citizens, but will encourage the belief that it is possible, by means of state enactments, to defeat the beneficent purposes which the people of the United States had in view when they adopted the recent amendments of the Constitution."
Over time, the words of Justice Harlan rang true. The Plessy decision set the precedent that "separate" facilities for blacks and whites were constitutional as long as they were "equal." The "separate but equal" doctrine was quickly extended to cover many areas of public life, such as restaurants, theaters, restrooms, and public schools. Not until 1954, in the equally important Brown v. Board of Education decision, would the "separate but equal" doctrine be struck down.
With the blessing of the Supreme Court, the floodgates opened in the years following the Plessy decision, almost every former Confederate state enacted "separate but equal" laws that merely gave the force of law to what had become a fact of life; slavery under a new name.
But who was Jim Crow?
It's thought that he was a slave from Cincinnati, Ohio; others say he was from Charleston, South Carolina. Another faction holds that Jim Crow derived from old man Crow, the slaveholder. A final group says that the Crow came from the simile, black as a crow. Whatever the case, by 1838, the term was wedged into the language as a synonym for Negro.
Thus, "Jim Crow laws" meant Negro laws.