Jim Crow laws were established by primarily southern governments once the Reconstruction Era ended, post Civil War. These laws were the basis for the concept of "separate but equal." These laws created in effect two classes of citizens, one with full rights and responsibilities (White America) and one with limited to no rights under the law (Black America).
These laws set up separate drinking fountains, places to sit on public places and on public transportation, along with limitations within the court system, such as a Black American being unable to testify in court against a White American. This was a legal method used to in effect reintroduce slavery into the south and areas of the United States that held the view that blacks should not have the same rights and protections as whites, even after the Civil War Amendments, 13th-15th, were enacted.
A 19th-century court case, Plessey v. Ferguson (1896), established the separate but equal doctrine as valid federal law when there was a lawsuit to end separate railcars for different races. This case established the precedent for all actions taken in the era of Jim Crow until the 1954 Brown v. Topeka Board of Education case that reversed the Plessey decision.
After the end of the United States Civil War in 1865, the country was united again and slavery was made illegal in all states. Unfortunately, while blacks were legally free men on paper, common prejudice and discrimination continued as whites -- especially Southerners, who were angry about losing the war and their bid for sovereignty -- placed blacks into a lower social class. To this end, the Jim Crow laws were invented to keep blacks from aspiring to a higher social position, or considering themselves equal with whites. The landmark legal case of Plessy v. Ferguson (1896) cemented the acceptability of "separate but equal" in many people's minds.
The most common example was segregation, which kept blacks from mingling with whites in most public places, including restaurants, churches, offices, bathrooms, and places of business. Segregation continued in one form or another until the 1950s. Examples of "whites-only" or "blacks-only" signs can still be seen in historic, refurbished, or abandoned buildings. Blacks were also prohibited from voting, which meant that they could not support candidates sympathetic to civil rights.
The main focus of the Jim Crow was to prevent blacks from mingling with whites, especially in marriage or politics. This stemmed both from the scientific beliefs of the time -- which were slowly proven wrong -- and from standard prejudice. Most whites shared these beliefs, and had no reason to doubt them aside from moral or ethical concerns. Because blacks were almost never involved with politics, there was no push to overturn the laws until after World War II, when the Civil Rights Movement began to gain real momentum.
Emerging from the Civil War, many Southern states were not completely comfortable with the idea of granting African- Americans complete rights and citizenship. The Jim Crow laws were a set of laws that ended up limiting African- Americans' rights in the South. These laws ended up making segregation, the division and separation of a social setting based on race and ethnicity, a major feature of life in the South. They were named after a minstrel character of Jim Crow, who was a loud and awkward character that was quite clumsy. The implication in the use of the name was that African- Americans were incapable of handling full freedom and needed laws and regulations to limit their interactions, keeping them checked and in place. Jim Crow laws were validated by the Supreme Court Case of Plessy v. Ferguson, a case that ended up making segregation the law of the land in its assertion that segregated and separate facilities and conditions were constitutional so long as they were equal in caliber.
As your "amp goes to eleven," you may have heard of the phrase "Separate but equal"? That's a Jim Crow law.
These laws were made by Southern state legislators to prevent blacks and whites from living together. These laws established the rule of the land that dominated the Civil Rights-era South known more commonly as segregation (which means "separation").
Other Jim Crow laws established separate black schools, communities, churches, and sections on a bus, within a restaurant, and other public facilities--even water fountains. The purpose of the laws, of course, were to delay civil rights and spread fear.
Enotes says it best:
Blacks had made some progress, but the laws that many southern state legislatures had written to prevent blacks and whites from living as equals—called Jim Crow laws—continued to separate the races in restaurants, schools, theaters, parks, and other public facilities in many states in the South. Those blacks who had migrated to northern and western states in an attempt to escape the legal restrictions of Jim Crow laws found that life in these new locations had similar restrictions because of customs based on racial prejudice, or a judgment or opinion based on a preconceived notions about race. Blacks in the North and West faced discrimination, or poor treatment based on race, in housing and the job market, among other areas. Police and citizens alike enforced the separation of races vigorously. Blacks who tried to mix with whites were arrested, beaten, or killed. Penalties for violence were rarely enforced when the crimes were acted out against blacks.
Jim Crow laws were laws that enforced the segregation of blacks and whites in the South.
Jim Crow laws first started coming into existence after Reconstruction ended in 1877. The system continued to grow until 1896. In that year, the Supreme Court declared that the Jim Crow system was legal -- that "separate but equal" accommodations for the two races constituted equal protection of the laws under the 14th Amendment.
After that, the Jim Crow system was expanded to include such things (in some areas) as different Bibles for black and white witnesses to swear on in Court. The system continued until the 1954 Brown v. Board of Education decision outlawed it in schools and the 1964 Civil Rights Act banned it elsewhere.