With the passage of the Kansas-Nebraska Act, a territory was created that stretched all the way north from the southern boundary of present-day Nebraska to include all of the remaining lands of the Louisiana Purchase. Eventually some limitations were enacted. Colorado appropriated a small corner of the original territory in 1861, and a few months later the Dakota Territory absorbed the lands north of the forty-third parallel. This left a long narrow strip of territory stretching to the Rocky Mountains. In 1863 the Idaho Territory was created, and it absorbed all of the land west of the 127th Meridian. That left the territory in roughly the same shape and with roughly the same boundaries as Nebraska has today.
Nebraska Territory map, with modern state outlines in white. NET Learning Services
But even this final territory was almost torn into two additional parts as a conflict developed between the settlers living north of the Platte and those living south of the Platte. The issue that brought the feud to a boiling point was the location of the territorial capital and the political power that would go with it. The more populous area south-of-the-Platte region wanted the capital to be located south of the river. They bitterly complained about the choice of Omaha City (north of the Platte) as the first capitol. The rivalry became so intense that in 1858, a majority of the members of the State Legislature stormed out of the legislature in Omaha and met in the town of Florence, five miles or so north. Eventually a South Platte convention was held at Brownville in 1859, and a formal request was sent to Congress asking them to allow the South Platte area to be annexed by Kansas. Their statement included the arguments that the soil and climate in Kansas and the South Platte area of Nebraska were similar, and that the Platte River was impassable and formed a natural boundary between Nebraska and Kansas. Eventually cooler heads prevailed and a compromise capitol location in what became Lincoln reunited the state.