"interim elections" is a very specific term that I believe has a specific definition.
What I am wondering, if it wasn't clear from the question I included in my first post, is if the term "interim elections" can be applied to local elections that occur between federal election cycles. Like the president is elected in 2008 and is up for re-election in 2012, but in 2010 there are Congressional and local elections. Would the 2010 elections be called "interim elections," or is this a misuse of the term?