What are the basic provisions of the Missouri Compromise?

Question

Why was it important to keep a balance of slave and free states in the nation?

I can't seem to find an answer that makes sense. Could someone help me out?

http://en.wikipedia.org/wiki/Missouri_compromise

http://en.wikipedia.org/wiki/List_of_U.S._states_by_date_of_statehood
With states and territories being added to the US rather rapidly (compared to the end of the 19th and beginning of the 20th centuries, anyway), neither side (pro- or anti-slavery) wanted the other side to have an advantage. Be sure to read Impact on political discourse in the first link above -- especially paragraph 3.

=)

Alright I think I understand now, but could you check my answers?

1. The Missouri Compromise essentially banned slavery above 36°30’ latitude line. In addition, the legislation admitted Missouri as a slave state and Maine as a non-slave state to keep it balanced.

As for the second question, I'm still a tad uncertain. The question seems obvious - there should be a balance so neither side feels like the minority - but I still think there is more to it.

It was important to keep a balance because of voting in Congress. Neither side wanted the other party to have move votes. In addition, it reflects the ongoing debate between states' rights and federal rights.

Question #2...They feared that ending this balance could lead to the domination of the industrial North with its preference for high tax on imported goods. The combination of these factors led the South to separate from the Union and thus began the American Civil War.