'The South' was a very large region in the lower eastern portion of the contiguous states of the USA. You may see a map in the following link: (link is not maintained) http://americancivilwar.com/pictures/comp1850.jpg
The South was a place which supported slavery, and had a wide-spread cultural deficiency in the appreciation of love, justifiably. The South used slaves to perform difficult manual labor for the benefit, mainly, of the people who 'owned' the slaves.
Today, the 'heartland' refers to areas of the USA which are still significantly influenced by this powerful history. The heartland is a place where love is secondary to selfish desires. The heartland also consequently has an overabundance of the most unfortunate people: the 'republicans'. 'Republicans', like their ancestors, possess a great lack of empathy for the life around them, causing relative harm and distress.