[craigbear]

I cringed at the time, but I have heard a few people who seemed to think that "Northern Ontario" meant anything north of the 400/11 interchange at Barrie, and even one or two people who deemed it to be anything north of Steeles Avenue. And Neil Young's "town in North Ontario", where all his changes were, is...Omemee. Er, no, not the north.

To answer the question, though: the Muskoka and Parry Sound Districts are kind of a "transitional" zone, that may be considered either "Southern" or "Northern" by different sources in different contexts. The provincial government treats Parry Sound, but not Muskoka, as Northern Ontario for the purposes of the Ministry of Northern Development and the Northern Ontario Heritage Fund; the federal government treats both Parry Sound and Muskoka as Northern Ontario under FEDNOR. And in terms of people's mental geography you may see Haliburton and even parts of Renfrew called "Northern" Ontario too, though no government agency at either level treats them as such officially.

And yeah, you'll see a lot of arguments about whether Eastern Ontario is part of Southern Ontario or not -- geographically it is, but culturally it's quite distinct from Central Ontario/GTA, so you'll get a very different answer on that question from a resident of Ottawa than you would from a resident of Sudbury.