The North Thompson River is the northern branch of the Thompson River, the largest tributary of the Fraser River, in the Canadian province of British Columbia. It originates at the toe of the Thompson Glacier in the Premier Range of the Cariboo Mountains, west of the community of Valemount. The river flows generally south through the Shuswap Highland towar…The North Thompson River is the northern branch of the Thompson River, the largest tributary of the Fraser River, in the Canadian province of British Columbia. It originates at the toe of the Thompson Glacier in the Premier Range of the Cariboo Mountains, west of the community of Valemount. The river flows generally south through the Shuswap Highland towards Kamloops where it joins the South Thompson River to form the main stem Thompson River.