Respuesta :
The answer is differences between the north and south because this is what led to the civil war. The word itself also gives clues. A section is part of a whole. So sectionalism would be dividing the U.S. into sections (North and South) Hope this helps and let me know if you have any more questions!
Sectionalism is a restriction of interest to a narrow sphere; undue concern with local interests or petty distinctions at the expense of general well-being. In this case the differences between north (abolitionist) and south (pro slavery).