Kansas was first settled by Americans in 1827 with the establishment of Fort Leavenworth. The pace of settlement accelerated in the 1850s, in the midst of political wars over the slavery debate. When it was officially opened to settlement by the U.S. government in 1854 with the Kansas–Nebraska Act, abolitionist Free-Staters from New England and pro-slavery settlers from neighboring Missouri rushed to the territory to determine whether Kansas would become a free state or a slave state. Thus, the area was a hotbed of violence and chaos in its early days as these forces collided, and was known as Bleeding Kansas. The abolitionists prevailed, and on January 29, 1861, Kansas entered the Union as a free state, hence the unofficial nickname "The Free State".
The first non-military settlement of Euro-Americans in Kansas Territory consisted of abolitionists from Massachusetts and other Free-Staters who founded the town of Lawrence and attempted to stop the spread of slavery from neighboring Missouri.
Missouri and Arkansas continually sent settlers into Kansas Territory along its eastern border to sway votes in favor of slavery prior to Kansas statehood elections. Directly presaging the American Civil War these forces collided, entering into skirmishes and guerrilla conflicts that dubbed the territory the nickname Bleeding Kansas.
Kansas was admitted to the Union as a free state on January 29, 1861, making it the 34th state to join the United States. By that time, the violence in Kansas had largely subsided, but during the Civil War, on August 21, 1863, William Quantrill led several hundred men on a raid into Lawrence, destroying much of the city and killing nearly 200 people. He was roundly condemned by both the conventional Confederate military and the partisan rangers commissioned by the Missouri legislature. His application to that body for a commission was flatly rejected due to his pre-war criminal record.
After the Civil War, many veterans constructed homesteads in Kansas. Many African Americans also looked to Kansas as the land of "John Brown" and, led by freedmen like Benjamin "Pap" Singleton, began establishing black colonies in the state. Leaving southern states in the late 1870s because of increasing discrimination, they became known as Exodusters.
In response to demands of Methodists and other evangelical Protestants, in 1881 Kansas became the first U.S. state to adopt a constitutional amendment prohibiting all alcoholic beverages, which was repealed in 1948.
In 1922, suffragist Ella Uphay Mowry became the first female gubernatorial candidate in the state when she ran as "Mrs. W.D. Mowry." She later stated that, "Someone had to be the pioneer. I firmly believe that some day a woman will sit in the governor’s chair in Kansas."