Oregon Country By abbyml11 Feb 22, 1819 Adam- Onis Treaty was signed wtih Spain Adam- Onis Treaty was signed wtih Spain May 6, 1824 Russia gives up its claim to Oregon Russia gives up its claim to Oregon May 6, 1836 Whitmans arrive in Oregon Whitmans arrive in Oregon May 6, 1840 Americans begin the "great migration" Americans begin the "great migration" May 6, 1846 United States and Britain agree to 49 degrees North as border of Oregon United States and Britain agree to 49 degrees North as border of Oregon