Most-populous Canadian province: Abbr.

ONT

This province is home to both Canada's capital city and its largest city, often called "The 6" in pop culture.

This clue asks for the abbreviation of Canada’s most populous province. Ontario holds that title, and its standard two-letter abbreviation is "ONT," commonly used in addresses or official documents. The "Abbr." in the clue signals that a shortened form is needed instead of the full name.