In 1822, McLoughlin had a new post built near where the confluence of the Willamette River and the Columbia. On the north shore of the Columbia a new headquarters, Fort Vancouver, became the centerpiece of a multi-post system where furs and supplies were funneled in and out of Fort Vancouver. Brigades of fur trappers would spend months in the wilderness trapping animals, then return with the pelts to fur posts such as Fort George, Fort Umpqua, Fort Walla Walla, Fort Nisqually, Fort Okanogan, and Fort Boise. Later the HBC would start the Puget Sound Agricultural Company to supply food staples to the venture. By the 1830s the Hudson's Bay Company was worried about American expansion into the region and, in an attempt to forestall it, made a policy that fur trapping brigades operating south of the Columbia River, especially in the drainages of the Snake River and Willamette River, would work to create so-called "fur deserts", where beaver stocks were rapidly and deliberately depleted. This policy, although successful in making beaver rare in the Willamette Valley, did not prevent American settlement.