Lawrence, Kansas
Prior to Kansas Territory being established in May 1854, most of Douglas County was part of the Shawnee Indian Reservation (created in 1830). During this period, the Oregon Trail ran parallel to the Kansas River, roughly through the area where Lawrence would eventually be situated and a hill known then as "Hogback Ridge" (i.e., Mount Oread, which sits on the water divide separating the Kansas and Wakarusa River). This area was used as a landmark and an outlook by those on the trail. While this territory was technically unopened to settlement prior to 1854, there did exist a few "squatter settlements" in the area, especially just north of the Kansas River.
Kansas and Missouri
Missouri was formed out of the Missouri Territory as a slave state during the early 19th century. Northern states wanting to slow the westward spread of slavery hammered out the Missouri Compromise with southern states anxious to keep slavery legal; this compromise ensured that any state directly west of Missouri would be a free state where slavery would be illegal. Thirty-four years later, Kansas became a territory, but Congress passed the Kansas–Nebraska Act that allowed the territory's residents to vote on whether or not slavery would be allowed. Both pro-slavery and anti-slavery boosters flooded into Kansas, but due to the state's proximity to Missouri, most were pro-slavery men from Missouri. They successfully stacked the vote to form a temporary pro-slavery government. Tensions resulting from this would lead to Bleeding Kansas, a violent and bloody civil war that would foreshadow the much larger American Civil War. Violence and guerrilla warfare continued for several years thereafter until the American Civil War ended, with many unjust killings and lootings performed by partisans on either side of the border. This violence and war deeply harmed the relationship between the two areas, even after Kansas attained statehood and the war had ended.