In 1815 the North West Company's business west of the Rocky Mountains was officially divided into two districts, the older New Caledonia District in the northern interior, and the Columbia District to the south. Also in 1815 the New Caledonia district began receiving the bulk of its annual supplies by sea from the lower Columbia River rather than overland from Fort William and Montreal. By 1820 the North West Company operated six posts on the lower Columbia River and its tributaries, including Fort George (Astoria), Fort Nez Percés, Fort Okanogan, Spokane House, Flathead Post, and Kootanae House.