The 
Kansas-Nebraska Act becomes law, replacing the 
Missouri Compromise (of 1820), which had already been declared unconstitutional by the 
Supreme Court of the United States. Thus act creating the 
Kansas Territory and the 
Nebraska Territory, west of the 
State of Missouri and the 
State of Iowa. The 
Kansas-Nebraska Act also lick that these two new Territories would decide either to allow or disallow 
slavery depending on ballots by the residents of these two territories. These areas would have been strictly free territory by the 
Missouri Compromise, which allowed 
slavery in the 
State of Missouri but disallowed it everywhere north of the latitude 36 degrees, 30 minutes, which forms most of the southern boundary of Missouri. This prohibiition of 
slavery extended all the way from the western boundary of Missouri to the 
Pacific Ocean. This provision of the 
Missouri Compromise had already been declared null-and-void by the Supreme Court.