north, northern

As a compass direction, north and northern are not capitalized:

            He lived north of the city.

            He lived in the northern suburbs.

Capitalize each term when it is used as a proper name or as part of a proper name, and if the region is widely known:

            The Civil War pitted the North against the South.

            He lived in Northern Virginia.

While the region (North) and residents (Northerner) are capped, NG style is lowercase for adjectives describing the region's features, such as chef, cuisine, and accent. 

When a U.S. region is used as a noun but in an adjective form, capitalization is preferred: a Northwestern-based company.