I'm fascinated by French politics, tell me why is that area more left-wing, as I thought (with my own limited knowledge) that the area there was more rural and from my experience, such places tend to support the right.
Actually, all I know about French political geography was taught to me by Hashemite.
If you are interested, he's got a blog specifically dedicated to the topic :
http://electionsfrance.wordpress.com/Anyways, France's political geography differs from that of most other countries in that the rural/urban divide hasn't played an important role in political cleavages. Rural areas may always have been a bit more right-wing, but you can find plenty of examples of left-wing rural areas, right-wing cities, right-wing rural areas and left-wing cities. Certain lands are famous for their rural progressivism (Limousin) and a city like Paris has long been a bastion of the hard right. I think the patterns of French political geography depend more on factors such as religion, socioprofessional situation (not really
social class like, say, in the UK) and historical traditions inherited from the Revolution or early 19th century. But things are much more complicated than that, and to learn more I can only advise you to read Hash's blog.