How was the Missouri Compromise of 1820 weakened in the middle of the nineteenth century? What ...

Answer: The ideal answer should include:
a. The Missouri Compromise established the latitude line of 3630 as the northern boundary of slave states created from the Louisiana Territory.
b. Under the terms of the Missouri Compromise, Kansas and Nebraska would have been admitted as free states.
c. The Kansas-Nebraska Act undermined the Missouri Compromise by allowing those two territories to vote on whether they wanted to be free states or slave states at the time of their application for statehood.
d. In the Dred Scott decision, the Supreme Court declared the Missouri Compromise unconstitutional.
e. The Missouri Compromise had ensured that the northern part of the Louisiana Territory would be free of slavery.
f. The Courts decision made that no longer possible.