As long as Union soldiers were in the South, things were alright for blacks. But when Union troops returned home, southern states were free to develop their own laws. They promptly began to deconstruct many federally-imposed reconstruction laws.
One of the first victims was the 1875 Civil Rights Act. That law, which had guaranteed equal rights to blacks in public accommodations, was declared unconstitutional by the United States Supreme Court. The rights act was replaced with laws like these:
The schools for white children and the schools for negro children shall be conducted separately. (Florida)
Books shall not be interchangeable between the white and colored schools, but shall continue to be used by the race first using them. (North Carolina)
It shall be unlawful for a white person to marry anyone except a white person. (Georgia)
The white and colored militia shall be separately enrolled, and shall never be compelled to serve in the same organization. (North Carolina)
The conductors or managers on all such railroad shall have power, and are hereby required, to assign to each white or colored passenger his or her respective car, coach or compartment. If the passenger fails to disclose his race, the conductor and managers, acting in good faith, shall be the sole judges of his race. (Virginia)
The officer in charge shall not bury, or allow to be buried, any colored persons upon ground set apart or used for the burial of white persons. (Georgia)
The unmistakable point of these laws was to keep controlling people - who were no longer slaves - as the South moved forward after the war.
By 1914, every southern state had "Jim Crow" laws.
Many of the first laws focused on separate railroad cars. Blacks were not allowed to sit in "white" railroad cars. Even Philadelphia, William Penn's northern "city of brotherly love," was governed by such laws.
But that isn't the worst of it. Passing laws is one thing; upholding them is something else. What is most troubling is the highest court in the country - the United States Supreme Court - issued discriminatory opinions which furthered the cause of legal segregation.