Oregon had this provision in it's Constitution:
"No free Negro, or mulatto, not residing in this state at the time of adoption of this constitution, shall ever come, reside, or be within this state, or hold any real estate, or make any contract, or maintain any suit therein; and the legislative assembly shall provide by penal laws for the removal by public officers of all such free negroes who shall bring them into the state, or employ or harbor them therein.In 1814 the Illinois legislature authorized the use of slaves in the salt mine. Free blacks migrating to Illinois after 1829 had to post a $1000 bond to prevent their being a "charge to the county", and Illinois in 1848 changed it's Constitution to prohibit the entrance of blacks. The "Black Law" of 1853 provided for the arrest of blacks staying more than 10 days in the state, along with a $50 fine, and their sale into indentured service (slavery) if they did not pay the fine. The law also prohibited the intermarriage of whites and blacks. Illinois has a database of slave records at "Illinois State Archives: Servitude and Emancipation Records"
The 1862 Revised Code of Indiana outlawed immigration of negroes and mulattos into the state, prevented blacks from entering contractual obligations, fined anyone employing a black $500, forbade interracial marriage, and prevented blacks from testifying in court against whites.
It wasn't just a southern thing.
Never said it was. But it was more common in the south. Every southern state had laws against blacks emigrating into the state. Not a single southern state allowed blacks to vote. Almost every southern state prevented blacks from practicing some trade or another. Almost every southern state had clauses in their constitution that prevented laws that would free slaves. As hard as it was up North, it was as hard or harder down south.