Louisiana Purchase
The land that would become the State of Nebraska, was part of the Louisiana Purchase, bought from France in 1803. The U.S. paid a total $15 million for 828,000 square miles, which basically doubled the size of the United States. President Thomas Jefferson soon organized an expedition to explore the new territory with the Lewis and Clark Expedition from May 1804 to September 1806.
Missouri Compromise of 1820
The question of slavery was a long standing issue in the United States, which divided the country even in the early 1800’s. With the Missouri Compromise of 1820, Congress agreed that future territories north of 36 degrees, 30 minutes latitude would be admitted as free territories and states, and land south of this line would be open to slavery. One exception to this was that Missouri would be admitted as a slave state (1821) and Maine would be admitted as a free state (1820). This would maintain the balance of free and slave states in Congress.
Kansas-Nebraska Act of 1854
The next big event for Nebraska was the passage of the Kansas-Nebraska Act of 1854. Congress was dead locked on the issue of expanding slavery into the western territories. The Missouri Compromise of 1820 had maintained a balance in the US Senate of an equal number of senators from free and slave states for over 30 years. The future territories of Kansas and Nebraska would upset that balance because both should be admitted as free territories, since they were north of 36 degrees, 30 minutes latitude set in the Missouri Compromise of 1820. No solution could be reached until Senator Steven Douglas of Illinois proposed to let the people of those territories decide the issue by popular vote (also called popular sovereignty). This was passed in 1854. This opened up old wounds and could allow any future territory or state to come into the Union as a slave state.
One former Congressman was very upset by this development, his name Abraham Lincoln. In 1858 seven debates were held in Illinois that received national intention in the press and raised the name of Abe Lincoln in national prominence.
Another outcome was that people from Missouri (a slave state) moved into Kansas to swing the vote toward slavery, while another group of “Free-Soilers” from northern states wished to swing the vote toward admitting Kansas as a free state. From mid to late 1850’s neighbor was fighting neighbor, which came to be know as “Bloody Kansas” or “Bleeding Kansas”. A strong argument can be made that the Civil War started in Kansas. One interesting point that tends to be forgotten, is when the southern states were seceding in late 1860 and early 1861, Kansas was admitted into the Union as the 34th state on January 29, 1861 as a free state.

Map of Kansas – Nebraska Territories 1854
Nebraska Statehood
Nebraska Territory created from the Kansas-Nebraska Act was huge. It initially ran from the Missouri River as the eastern boundary to the rocky mountains on the west, and from the southern border with Kansas to the Canadian border on the north. This made the territory larger than the state of Texas. In 1861 however, the territory was carved up to add to the future territories of Colorado, Dakota, and Washington. In 1863 it was divided again to contribute to the new Idaho territory. Nebraska became a state after the Civil War on March 1, 1867.