The United States gained control of Oregon and Texas through diplomatic agreements and annexation. Oregon was divided between the US and Britain along the 49th parallel. Texas was annexed after threats from Britain prompted Congress to approve annexation. The Mexican-American War was caused by a border dispute between the US and Mexico over land between the Rio Grande and Nueces Rivers. The US acquired California, New Mexico, and parts of modern Arizona and Colorado after defeating Mexico in the war. Cultural influences were exchanged as English settlers integrated Mexican and Native American practices, words, and some laws into the Southwest.