Adopted in 1927, modified 1961. Admitted to the Union January, 1861 as the 34th state. Kansas was annexed to the U.S. with the Louisiana Purchase of 1803, although the southwestern portion was formerly Spanish and Mexican, then Republic of Texas territory annexed after the War with Mexico 1846-1848. The Kansas Territory was organized in 1854 by the U.S. Congress with the Kansas-Nebraska Act of 1854. The Act voided the Missouri Compromise of 1820, resulting in conflicts between free state, or slavery abolitionists and pro-slavery settlers.