What changes did the missouri compromise bring to the u. s. map?

In the years leading up to the Missouri Compromise of 1820, tensions began to rise between pro-slavery and anti-slavery factions within the U.S. Congress and across the country. They reached a boiling point after Missouri’s 1819 request for admission to the Union as a slave state, which threatened to upset the delicate balance between slave states and free states. To keep the peace, Congress orchestrated a two-part compromise, granting Missouri’s request but also admitting Maine as a free state. It also passed an amendment that drew an imaginary line across the former Louisiana Territory, establishing a boundary between free and slave regions that remained the law of the land until it was negated by the Kansas-Nebraska Act of 1854.

The Missouri Compromise was an effort by Congress to defuse the sectional and political rivalries triggered by the request of Missouri late in 1819 for admission as a state in which slavery would be permitted. At the time, the United States contained twenty-two states, evenly divided between slave and free. Admission of Missouri as a slave state would upset that balance; it would also set a precedent for congressional acquiescence in the expansion of slavery. Earlier in 1819, when Missouri was being organized as a territory, Representative James Tallmadge of New York had proposed an amendment that would ultimately have ended slavery there; this effort was defeated, as was a similar effort by Representative John Taylor of New York regarding Arkansas Territory.

Southerners like Senator William Pinkney of Maryland held that new states had the same freedom of action as the original thirteen and were thus free to choose slavery if they wished. After the Senate and the House passed different bills and deadlock threatened, a compromise bill was worked out with the following provisions: (1) Missouri was admitted as a slave state and Maine(formerly part of Massachusetts) as free, and (2) except for Missouri, slavery was to be excluded from the Louisiana Purchase lands north of latitude 36°30′.

answer; /// i believe that the correct answer is (d)the huang he river valley;