The "Deep South" is a term used to refer to a region of the Southeastern United States typically considered to include Georgia, Alabama, Louisiana, Mississippi, and South Carolina, with some definitions including Texas, Florida, Tennessee, and North Carolina, as well. This term came about to describe the Southern states that were the most deeply rooted and reliant on slavery; in the 1800s and early 1900s, the region was also referred to as the "Cotton states" for this reason. In "Ireland Makes Irish," Bowen discusses Irish houses, both their architecture and their cultural/historical significance, and says that she has "been given to understand that these Irish houses – or rather, perhaps, the way of life that they stand for – are not unlike some in the deep South of the United States." She speaks earlier in the paragraph of Irish houses and estates carrying with them a sense of feudalism and self-sufficiency, which she could be comparing to Southern plantation homes. She mentions most Irish houses being of Georgian architecture, which certainly bears many similarities to Deep Southern plantation houses.
Irish House: 
Southern House: 
. Georgian architecture: 
Map of the Deep South: 