 Adams favored the annexation of the entirety of Oregon Country, a disputed region occupied by both the United States and Britain, and was disappointed when President Polk signed the Oregon Treaty, which divided the land between the two claimants at the 49th parallel.Polk's expansionist aims were centered instead on the Mexican province of Alta California, and he attempted to buy the province from Mexico.The Mexican government refused to sell California or recognize the independence and subsequent American annexation of Texas.