Manifest Destiny expressed that the United States was destined by God to expand its dominion and spread democracy and capitalism across the North American continent. This period of history had some major events, they are:
The declaration of independence of Texas from Mexico: This declaration was signed in the Texas Revolution. The main reason for the independence was that there was a big number of Americans settlers that were in favor of slavery and Mexican law prohibited it.
The Battle of Alamo: This battle was a pivotal battle in the Texas Revolution in February 23rd to 1836 to March 6th of 1836. The Mexicans won the battle killing all the Texas soldiers inside the fort Alamo.
Aroostook War: Also called Pork and Beans war was a dispute between the US and Britain over the location of the border between the British Colony of New Brunswick and the US state of Maine. Some Americans were arrested by Canadian officials.
Webster-Ashburton Treaty: The Webster-Ashburton Treaty was a treaty signed on August 09 of 1842 that solved border issues between the US and British North American Colonies - that later became Canada -, it came after the Aroostook War.
Congress passes Tariff of 1842: The Tariff of 1842 also known as a protectionist tariff adopted by the US to reverse effects of the Compromise Tariff of 1833. This tariff had a big impact, it declined the international trade in 1843, It cut in half their 1842 levels and exports and dropped trade patterns by 20%.
The United States annexes Texas: In 1844 the US Congress agreed to annex Texas as the 28th state. It contributed to the Mexican-American War.
Congress has presented with Wilmot Proviso: The Wilmot Proviso was a proposal to prohibit slavery in the territory that was annexed by the US after the Mexican War.
Mexican War and the capture of Mexico City: The US and Mexico disagreed on the border between Texas and Mexico. Congress declared war in 1846. Americans captured Mexico City in 1847.
Treaty of Guadalupe: It was a peace treaty signed on February 2nd of 1848 between the US and the Mexican Republic after the Mexican American War. It also settled limits between the borders.