What impeded the effectiveness of the fourteenth amendment in providing equal protection and citizenship rights?

The 14th Amendment was issued around the Reconstruction period, basically to provide equal rights to slave descendants after the Civil War, granting  citizenship to all people born or naturalized in the country, and it has become kind of the main provision in the USA Constitution to enforce Civil Rights and prevent violations; but it was only until the Civil Rights Era around the 1950s and 1960s that really became effective; affairs such as "Jim Crow laws", white supremacy organizations, multiple segregation policies, voter suppression mechanisms such as "The white primries", poll taxes and some others like literacy tests vastly impeded the effectiveness of the Amandment for a long time.