Missouri became a slave state, Maine became a free state, and the Missouri Compromise line was created.
What was the cause:  

If Missouri joined alone the states would be uneven. 
What was the effect: 

Any state north of the Missouri Compromise line was free, any state south of it was slave.

California becomes a free state, land won in Mexico war would be territories and would vote on slavery, slave trade in Washington D.C. would end, and everyone had to help catch runaway slaves.
What was the cause:

The North wanted California as a free state but the South wanted it as a slave state. The U.S. had a lot of land they didn’t know what to do with.
What was the effect:

South loved the compromise but the North hated it.

Kansas and Nebraska would become territories and they could vote for slavery.

What was the cause: 

Stephan Douglas wanted to build a transcontinental railroad 

What was the effect: 

Many Missourians illegally voted for slavery in Kansas.

He killed 5 pro-slavery men. Raided a federal arsenal.
What was the cause:

He found out his family was targeted for an attack. He thought that raiding the arsenal would help free slaves.
What was the effect:

North thought that Brown was a hero, the South thought that he was a lunatic.

Dred Scott was a slave and in 1856 he sued for his freedom.
What was the cause:

Scott was brought to a free state and should’ve been free but his owner illegally kept him.
What was the effect:

The court didn’t give Scott his freedom but he got his freedom bought later

Florida, Tennessee, Texas, Louisiana, Arkansas, Georgia, Alabama, South Carolina, North Carolina, Virginia, and Mississippi and seceded.
What was the cause: 

South seceded because they thought that Lincoln would abolish slavery 
What was the effect:

All of the southern Union forts were taken over by the Confederates

1st battle of Civil War. Lasted 33 ½ hours
What was the cause:

Union troops wouldn’t leave Fort Sumter
What was the effect:

The Civil War had started