Northeastern settlers were slower to pioneer than their Southern counterparts, but they filled the northern halves of Illinois and Indians, branching into Iowa, Wisconsin, and Minnesota in the 1830s through the 1850s. They were supplemented by large waves of German and Scandinavian immigrants, who had no use for slavery and states' rights. By 1860, the South had effectively lost its business and cultural ties with the Midwest. The exceptions were those counties along the Ohio and Mississippi rivers, where there were strong Copperhead sentiments.
But people who were born and grew up on the frontier didn't have much loyalty to the states where their parents were born. If you went directly from Boston or Charleston to the west, you might retain all the characteristics and loyalties of the state where you were born, but if you were born and raised in Kentucky -- then considered a Western state -- or in the Appalachians, you were born a Westerner.
Lincoln, who was born in Kentucky, didn't identify with Virginia, where his parents were born. That's not surprising. Some people became pioneers because they really didn't like the wealthy slave owning planters who controlled their states. That may have been one reason why they left.
Southern identity also took some time to develop. And in fact, in 1830 most Southerners probably sided with Jackson and the Union, rather than with South Carolina. Jackson, Clay, Benton and others were considered as much Westerners as Southerners, and had no sympathy with the nullifiers.
So if the South had seceded in 1830, would Illinois and Indiana and Missouri have gone with the South? Well, the premise is a little off. The whole South wasn't going to secede in 1830. The South wasn't going to go out with the South. So why would the Midwest join one or two states that tried to secede?