Odd Illegal Immigrant Factors

I looked at a map of the concentration of illegal or undocumented workers. You naturally find them in border states. That is understandable.

But you also find them in states such as New York and New Jersey and Illinois, yet not heavily in states that surround them. Such as Pennsylvania, Ohio, Missouri and Michigan, for example. You do not find them heavily concentrated in Mississippi. But next door in Alabama, Louisiana and Arkansas, there are larger percentages of the undocumented. Nor are they heavily populated in North and South Dakota or Montana.

I have covered all varieties of farming and manufacturing states and climates.

Would it be social benefits or schooling or legislation? There must be a particular combination of reasons in those states.