Oxford appears multiple times in "North and South". It is where Mrs. Hale wished they had moved, where the most esteemed and educated men are, and where Mr. Bell thinks Margaret belongs. While Oxford is mentioned many times, the audience is never actually taken to Oxford, its merely a common place.
Oxford was the largest town on the Upper Thames, and one of the most industrialized. It too ahd many factories and even a train railway. It was a center for industrialization and due to it's marshy landscape and poor sewage for the lower class, this was the place the word "slum" originated. Yet it was highly revered due to its University, and was known to also be a center for education and modernity.
Oxford is just one of the many places that fall into the "grass is always greener" feeling that all the Hale's seem to live by, especially Maragret. While she never goes to Oxford it is metnioned constantly by the famiy and community that surround her. Margaret follows suit with many places. When she wishes to be at Helstone she is with her Aunt, when she wants to be with her Aunt she is in Helstone. When she is Milton she wants to be on Oxford or Helstone and when she's back at Helstone she wishes to be at Milton. Oxford was a city that was bigger and better, but was it actually? We see Margaret adapt to her enviornment no matter what it is, and grow to love it for what it is. While things change, Margaret changes and while she yearns for a place other than Milton, such as Oxford or to a greater degree Helstone, she is putting roots in Milton. It is possible to like where you live and make a difference even if it's not what you had in mind. That is a lesson that is a hard pill to swallow initially for Margaret, but as time goes on, she grows to care for Milton.
Sources
Oxford | England, United Kingdom | Britannica
2015-09-11-1441987641-5274129-Oxfordshutterstock_83319043.jpg (3719×2480) (huffingtonpost.com)