British Columbia
Obviously Alaska is north of Idaho. States in the "Lower 48" that have significant amounts of terrain farther north than the northern border of Idaho include Washington and Maine. Minnesota has a little tip that seems to be slightly farther north than Idaho, but if it is, it's not by much. The Canadian province of British Columbia abuts Idaho's northern border.
Washington is bordered by Oregon to the south, Idaho to the east and the Canadian province of British Columbia to the north.
Idaho borders British Columbia
Montana if you are in Wyoming or southern or central Idaho Canada if you are in Canada or the dakotas or northern Idaho
Idaho is the state on the Canadian border that is home to Coeur d'Alene, Downey, Idaho Falls, and Pocatello.
Idaho does
Washington, Idaho, Montana, and Alaska are the US states that border British Columbia. British Columbia is a Canadian province. Its capital is Victoria.
Canada borders Washington state to the north
The State of Montana is bordered on the East by North Dakota and South Dakota, to the South by Wyoming, and to the West and South by Idaho. The Northern border of Montana is also the U.S./Canadian border (Canadian Provinces of Alberta and Saskatchewan).
Washington State's northern border with Canada is a straight line from Blaine WA to its eastern border with Idaho. That northern border line is the most northern point.
Idaho and Oregon