Kansas was first settled by European Americans in 1812, in what is now Bonner Springs,but the pace of settlement accelerated in the 1850s, in the midst of political wars over the slavery issue. 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. After the Civil War, the population of Kansas grew rapidly when waves of immigrants turned the prairie into farmland.