The Missouri Compromise of 1820 was an effort by the U. S. Senate and House of Representatives to maintain a balance of power between the slaveholding states and Free states. The slaveholding states feared that if they became outnumbered in Congressional representation that they would lack the power to protect their interests in property and trade. In 1819, the slaveholding territory of Missouri applied for admission to the Union. Northern states opposed it, feeling that Southern slaveholding states held too much power already.
Congressional debates went on for a while until the District of Maine, originally part of Massachusetts, sought statehood. Henry Clay of Kentucky, the Speaker of the House, maintained that if Maine were to be admitted, then Missouri should be, too. From this came the notion that states be admitted in pairs, one slave and one free. Thus came the 36 30 line which gave congress a guideline in the fact that if a new state comes about the line above means that it will be free and line below a slave state. For nearly 30 years, the compromise worked, with two states being admitted together, one slave, one free.
Then, in 1850, California was admitted as a stand-alone free state, upsetting the balance 16–15, in exchange for a Congressional guarantee no restrictions on slavery would be placed on the territories of Utah or New Mexico and passage of the Fugitive Slave Act, which required citizens of all states to return any runaway slaves to their masters. In 1857, the U. S. Supreme Court ruled Congress had no right to prohibit slavery in territories, as part of the decision in the Dred Scott case. The Kansas-Nebraska Act of 1854 repealed the 36-30 dividing line for slavery in the Louisiana Purchase area.
I chose the Missouri compromise as the most significant from the rest since it was the one of the huge stepping stones leading to the civil war, which dramatically shaped the country, whilst Erie canal The Andrew Jackson Bank War and 1848 gold rush did have some significance but not as much, for example the Erie canal did have technological advancement and it was the first time we invented something and did not the help of England (wet cement). The gold rush 1843 encouraged much more westward movement and was the first time gold was not owned by the government but rather the people.