Summary
The Northwest Ordinance of 1787 created the territory that contained the future states of Ohio, Illinois, Indiana, Wisconsin, Michigan, and an eastern portion of Minnesota. Part of the ordinance was the explicit prohibition of slavery in this new territory. Still, in spite of the ban on slavery, some states that were formed out of the Northwest Territory attempted to codify white supremacy into their laws. These discriminatory laws, generally referred to as Black Codes, resemble the Jim Crow Laws that would be enacted following the period of Reconstruction.
For example, the 1851 Constitution of Indiana prohibited Black people from entering the state. An 1853 Illinois law also attempted to prevent the interstate travel of free Black people. Other laws prohibited Black people from testifying in court cases involving white people. When public education spread through these and neighboring states, laws were passed preventing Black students from attending these schools. Ultimately, these laws were designed to discourage Black migration into the states immediately north of the Ohio River. When Oregan became a state in 1859, its constitution prohibited slavery, but also called for the "effectual exclusion" of Black people from the state entirely.
By the 1820s, New York and Massachusetts allowed their free Black residents to be citizens of the state. The differences in policy between the Northwest Territory states and the New England states brought new questions and challenges to the Privileges and Immunities Clause (Article IV, Section 2) of the Constitution, which states that citizens of each state are entitled to the privileges and immunities of the several states. So a constitutional argument could be made that Illinois cannot keep African Americans who are citizens from traveling in the state because it is a violation of the Privileges and Immunities Clause. The rights of free Black people remained very unclear during this period.
During the Reconstruction Era following the Civil War, state governments in the South pass hugely discriminatory labor laws and unleash violence against the newly freed Black population in order to keep their labor force in place. The 14th Amendment came out of this conflict, as well as the Civil Rights Act of 1866, and it applied not only to the former slave states, but nationally, repealing or delegitimizing Black Codes not only in the South, but also the West and Midwest.
The 14th Amendment has continued to have significance in movements for Civil Rights, not only having to do with race, but also gender, sexuality, and even college admissions systems.
Suggested Reading
Masur, Kate. Until Justice Be Done: America's First Civil Rights Movement, from the Revolution to Reconstruction. W. W. Norton, 2021.
Webinar - Equal Protection, Reconstruction, and the Meaning of the 14th Amendment (2023)