The basic lesson here is very easily understood: regions/states/counties are either feminine, masculine, or plural, (just as countries and continents). "En" is used to express "in/to" with feminine regions/states/counties ; "dans le" is used to express "in/to" with masculine regions/states/counties. Suisse cantons have their own system which is also very clear.

I think the challenge all of us learners are having is knowing whether an area is masculine or feminine. I was able to answer both questions in my first test of this lesson only because I was familiar with la Bretagne, (from "la Grande Bretagne"); and having lived in Nimes and Montpellier as an exchange student, (many, many years ago), I remembered that it was "Le Rousillon"

Is there a website or a list somewhere of all the U.S. states, the provinces and regions of France, Canada, Great Britain, etc. and their genders? It would be immensely helpful. For example, I learned from the lesson examples that Illinois and New Jersey are masculine, but I don't know about the state of Missouri where I live, (just across the Mississippi from Illinois).

Thank you for your help. Even though it is a bit challenging, this is a great topic.