along the Mississippi River extends about 50 miles (80 kilometers) to the south, all the way to the 36th parallel north, and about 30 miles (50 kilometers) inland. This was because politicians in that region along that major river felt that it would be advantageous to be located in Missouri rather than in the Arkansas Territory, which became the State of Arkansas in 1836. The parallel 36°30′ then forms the rest of the boundary between Missouri and Arkansas. The Missouri Compromise of 1820 established the latitude 36°30′ as the northern limit for slavery to be legal in the territories of the west. As part of this compromise, Maine (formerly a part of Massachusetts) was admitted as a free state. This addition maintained the balance of power in the U.S. Senate between the free states and the slaveholding states. The bulk of Missouri lies north of the 36°30′ line, but Southern planters who lived in southeastern Missouri supported slavery, especially for farming on their cotton plantations. Hence, part of the Missouri Compromise arose from this. Also, the slave states of the Southern United States wanted to have the support of another slave state so the Senate could not abolish slavery in the United States. This situation remained in effect for decades because as the free states of Michigan, Wisconsin, and Iowa were admitted to the Union, the new slave states of Arkansas, Florida, and Texas were also admitted. When the Republic of Texas joined the United States in 1845 as a slave state, it was required to cede all of its claimed land north of the 36°30′ latitude to the Federal Government. Over the following half-century, this land became parts of Kansas, Colorado, New Mexico, and Oklahoma. The Compromise of 1850 confirmed that the 36°30′ parallel was the northmost boundary of Texas. Then Kansas was admitted to the Union as a free state in 1861. The creation of the New Mexico Territory and the Utah Territory in 1850, the Kansas Territory in 1854, and the Colorado Territory in 1861 moved the boundaries of one of the western territories, New Mexico, north to the 37th parallel north. New Mexico Territory was eventually split in two states, New Mexico and Arizona, which were admitted in 1911–12, but this was long after the 13th Amendment had abolished slavery in all of the United States. The gap between the northern boundary of Texas on the