States' Rights is defined as the rights and powers held by the individual states rather than a centralized power in the federal government. In the Civil War era, this struggle focused heavily on the institution of slavery and whether the federal government had the right to regulate or even abolish slavery within an individual state. The sides of this debate were largely drawn between northern and southern states, arguing over the constant conflict between government intervention and economic liberty, thus widened the growing divide within the nation. In particular the changing attitudes toward slavery; Northern abolitionists began vehemently assailing the institution and the states that continued to practice it, while the South retained their state right to decide for themselves. Whilst the people in the north believed in a strong federal government, the southern states believed that each state government should have more power, and should be able to make important decisions on its own. Southerners claimed that the federal government wasn't allowed to to stop them for having slavery because of the 10th Amendment. "The powers not delegated to the United States by the Constitution, nor prohibited by it to the States, are reserved to the States respectively, or to the people."
The debate over slavery intensified, creating a widening gap between slaveholding and non-slaveholding states.
In 1845, outgoing President Tyler added Texas to the country, which angered Mexico who claimed it was theirs. This resulted in an ongoing border dispute between the USA and Mexico. President Polk further provoked Mexico, as he had designs on California and New Mexico. In 1845, Polk sent troops to the disputed area, hoping that the Mexicans would attack. They did just that: Mexican troops ambushed US troops, killing or wounding sixteen men. This was all part of Polk's plan; he took it straight to Congress and said Mexico "shed American blood on American soil." Congress was quick to declare war. Although the USA had a smaller army, it had a stronger industrial base and Mexican forces were not well trained or equipped. A direct result of America's victory was its massive increase in land (California, New Mexico, present day Nevada, Utah, most of Arizona and parts of Colorado and Wyoming), written in the Treaty of Guadalupe-Hidalgo.
The Mexican-American war introduced a new conflict between the North and the South as to whether the new states should be considered slave states or free states, intensifying the North-South divide as the land was undecided, and would tip the balance between free and slave states.
Abolitionism was a movement based on the desire to end slavery. It did not peak in support until after 1830 when a new movement of Militant Abolitionism formed. Tactics including use of moral suasion, trying to persuade others that slavery was wrong, without violence. Abolitionists wanted to change the hearts and minds of others by means of writing, speaking tours, and petitions to congress. Abolitionism brought slavery into focus, polarizing the slave debate that had been often ignored, but had limited political success. It intensified the sectional divide between the north and the south, as much of the south unified over the common defense of slavery and changed southern mindsets about slavery from "a necessary evil" to "a positive good." Over time, abolitionists grew more strident in their demands, and slave owners entrenched in response, fueling regional divisiveness that ultimately led to the American Civil War. Although slavery existed in all the thirteen colonies, slavery was most important in the South. The climate in the South was more suitable to plantation agriculture, while the Northern climate was not. " 'King Cotton' ensured that slavery survived and thrived." Cotton production in the South had a major contribution to the American economy. In fact, the importance of cotton in the economy ended up surpassing that of any other plantation crop contributing to the economy. It was so important in the American economy that it was given the name 'King Cotton' in society. "No power on earth dares to make war on cotton. - Cotton is king," said Senator James Hammond in 1858.'King Cotton' ensured that slavery survived and throve. In 1790, only 9,000 bales of cotton were produced in the USA. Eli Whitney's invention of a cotton engine in 1793 revolutionised Southern agriculture. It enabled short-fibre cotton (the only cotton which easily grew in the South) to be quickly separated from its seed. Suddenly, it became highly profitable to grow cotton and Southern farmers cashed in. By the 1830's, the South was producing 2 million bales per year.Cotton soon outstripped all other plantation crops in economic importance. From 1815 to 1860, cotton represented more than 50% of all US exports. Such was the demand (mainly from textile manufacturers in Britain), and such were the profits, that the cotton belt spread westwards - to Kentucky, Tennessee, Alabama, Mississippi, Arkansas and Texas. Cotton production needed a large amount of unskilled labour. Slave labour was ideal. Cotton and slavery, therefore, were interlinked. Southerners migrating westwards either took their slaves with them or purchased surplus 'stock', mainly from the upper South. In the 50 years before 1860, perhaps 1 million slaves relocated from the upper South to the lower South and from south-eastern to south-western slave states." The Kansas-Nebraska Act, introduced by Senator Stephen A. Douglas was a bill designed to appeal to the South, proposing:
1) The repeal of the Missouri Compromise, introducing popular sovereignty instead
2) It divided the Nebraska territory in two: Kansas and Nebraska. There was little chance of slavery taking hold in Nebraska (the climate was too cold for plantation agriculture), but it seemed possible it might spread to Kansas.
Douglas, a great believer in popular sovereignty saw no problem in letting the people of Kansas-Nebraska decide their own fate. He was convinced that they would not vote for slavery, and as a supporter of manifest destiny he did not want settlement of the West stalled by sectional controversy. He miscalculated, and the North was angered: it was proof to many Northerners that the Slave Power Conspiracy (A Northern notion that Southerners were plotting to expand slavery). Bill became law in May 1845, but by failing to predict the extent of Northern outrage it generated, Douglas weakened his party, damaged his presidential ambition, and helped revive North-South rivalry. It became a key factor in the demise of the Whig party, it creates a divide within the party which before had avoided the topic of slavery: their strategy of not speaking to the issue of slavery they alienate their supporters in the North. Whigs had tried to take a pro-catholic stance to attract the masses of immigrants from Ireland and Germany, which backfires as the anti-immigrants leave, and most of the catholics vote democrat anyways. Due to nativism and opposition to the Kansas-Nebraska Act, the Whig party had its demise.
By repealing the Missouri Compromise, people in the anti-slavery north viewed Congress as allowing the south to exert more control in Congress, and they resented it. It also made the south seem more aggressive in their pro-slavery sentiments. The repeal of the Missouri Compromise lead to the formation of the anti-slavery Republican party. The act also led to a further increase in the level of passion over the slavery issue, both in words and deeds.