The 19th century was very important for the history for America. It saw the rise of populism, Jacksonian democracy and the creation of the 'Manifest Destiny', invented in 1845 - an idea that the United States is destined to expand and spread democracy and capitalism across the entire North American continent. The rapid expansion of the United States intensified the issue of slavery as new states were added to the Union, leading to the outbreak of the Civil War. The beliefs that proceeded from 'Manifest Destiny' and its results were usually catastrophic to anyone who opposed the American expansion.
Growth of a country with the purchase of the states was one of the biggest indicators of territorial expansion and national union. The first big expansion began with the Louisiana Purchase in 1803. It was Thomas Jefferson's most significant occurrence in his first Administration. The Louisiana Purchase is a very important event in United States history, not only by doubling the size of the United States, but by having a considerable effect on the young nation’s foreign and domestic affairs, while also managing to seal the union of East and the Middle West. The acquisition of this region was considered by the democratic republicans as an extension to the empire. And even though the southeastern border with Spanish Florida led to a conflict, it was resolved when it was also bought in 1821.
Another important way of cementing national union was how Louisiana Purchase intensified American migration to the west that was already ongoing. Anglo-American agreement in the 18th century was generally confined to the eastern part of the continent. It made its boldest inroads where easy internal transportations were allowed by rivers. Also, expanding from the eastern Atlantic to the western Pacific was a really hard procedure. As population started to increase, the east coast started to get very crowded and overpopulated. Farmers made a decision to move west as they were persuaded by less expensive lands. And this represents the new beginning for America.
On the other hand, slavery was a big problem when it comes to national unity. For example, Texas had petitioned for the entry in the Union in 1836, and the arguments that were ensuing in Congress over the unevenness between free and slave states got its entry delayed into the Union. The problems of annexation were connected to the issues of slavery and expansion. Southerners looked at the annexation of Texas as the way to broaden the cotton manufacture and as a way to gain additional two slave state votes in the Senate. Some Northerners believed that the annexation of Texas was the way to extend American territory south into Mexico and South America as a part of some Southern scheme, therefore conceiving endless number of new slave territories.
In conclusion, even though this period of America featured many horrible things such as slavery and child labour, with an economy that was growing so rapidly and the brand new territories that have been acquired, it still managed to bring people together and unite them like never before.