[Bubba Ho-Tep]

Those laws were not enforced.

Neither were Illinois', apparently.

They were enacted during the period when the northern states were trying to eliminate their own black populations through structures manumission laws.

What are "structures manumission laws"?

And the free black numbers in the census are known to be bogus. Free black men listed their wives and children as slaves for legal reasons.

A) Source?
B) What legal reasons would those be? The not-enforced laws demanding freed blacks leave the state?

[antinomian]

Those laws were not enforced. Neither were Illinois', apparently.

Yes they were. They prevented immigration and were quite effective.

What are "structures manumission laws"?

Sorry. structures=structured.
The structured manumission laws specified that slaved born after a certain date had to be freed when they reached a certain age. The age was always when the slave would be at his greatest value and the expectation was that owners would sell them rather than free them.

The southern states protested this practice but there wasn't much they could do.