I assume you like money? Most people like money. I think the Southern slave holders back in the 1850s liked money too, so I think they would do whatever brought them the most value for their effort.
Slaves cost around $1,000.00 in 1850 money, which is roughly equivalent to $100,000.00 today. If you have the choice between growing wheat or cotton, you would be a d@mned fool if you chose wheat. The money was in cotton. That's why it was the dominant use of slaves in that era.
People in that era were not stupid. They would not waste slaves in Kansas when they could make higher profits by using them in Mississippi or Louisiana.
So there we re a bunch of stupid slave owners in Maryland , Kentucky, Delaware, and saintly ol Virginia? Hummmm?y