The American Civil War (1861–1865) became inevitable when the South opened fire on Fort Sumter in 1861.
By 1861, there were many obvious differences between the North and South. For example, the South's labor force was primarily agricultural. But less than half of the North's laborers worked in agriculture. The South was rural while the North had most of the largest urban centers. Slavery was an important institution in the South and Southern leaders were almost always slave owners. Although there were many differences between the two regions, the United States was one nation in 1860. Not until shots were fired at Fort Sumter did they become enemies on the battlefield.
There had been numerous factious quarrels between the North and the South before war erupted, and these occurred between 1820 and 1860. In 1820, the Missouri Compromise dealt with the question of slavery in the West.
Separation of powers divides the national government into three branches. Checks and balances refers to the power that each branch exerts over the others and keeps them from becoming more powerful than one another.
As a result of the Boston Tea Party, the British shut down Boston Harbor until all of the 340 chests of British East India Company tea were paid for. This was implemented under the 1774 Intolerable Acts and known as the Boston Port Act