Northerners and the North

You have some flexibility. I have the same issue in my novel, with latecomers to the colony being called tressers. Then there are the class divides: owners, know-profs, and labor. The original colonists are called Founders.

Just look for some examples in real life. I decided to use Founders as their official name, like Americans. But tressers (short for trespassers) is more like undocumented aliens so I chose to make that a label rather than a proper noun. The same with the class divides, they're not formal names but rather references to groups of people like you might call farmers or teachers.

But I could have made them formal names and it wouldn't have been wrong.

Look at how the South is used and people in the south and follow suit.

8.46 (16th ed) of the CMoS offers this:

the South, southern, a southerner (of a country), [but] the South, Southern, a Southerner (in American Civil War contexts).

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Fallen said:

8.46 (16th ed) of the CMoS offers this:

Click to expand...

Thanks. That reinforces my conclusion, which took an awful lot of pondering, that there were choices that weren't rigidly right/wrong.

General rule of thumb:

Direction or people - don't capitalize. (go north, a northerner.)

Region - capitalize. (the North, the West)

I'm pretty sure Northerner needs to be capitalized.

I'm a north-westerner from southern Montana who now lives in central Oregon.
I've been in this fight before and learned no advice on directional capitalization pleases everyone.

In fact, capitalization is a slippery slope generally making people crazy.