Was Expansion Inevitable

Treaty of San Lorenzo, Spain

1795

Many Americans moved westward around parts like Ohio and Tennessee where they would become dependent on the Mississippi River which was controlled by Spain. This treaty granted Americans the right to use the mouth of the river but these rights were later revoked in 1802 and with the inevitability of expansion this led Thomas Jefferson in search of purchasable land, in this case New Orleans which would allow for access to the mouth of the Mississippi river.
(Britannica Louisiana Purchase)

Louisiana Purchase

1803

With Thomas Jefferson in search for land to be purchased and France in need of money they offered up the entire Louisiana territory. Thomas Jefferson purchased it without known authority but it was revised in the Constitution to be allowed. This purchase was the most critical to the expansion of the U.S. as it doubled the size of the U.S. at the time and allowed for American influence to officially carry westward.
(Britannica Louisiana Purchase)
(5.4 Land Acquisitions)

Indian Removal Act

1830

During Andrew Jackson's term as president many settlers wanted to move into Native American land and pushed for their removal. Andrew Jackson having a negative view towards Native Americans allowed for the Indian Removal Act which led to the "Trail of Tears." This allowed for settlers to freely expand into new lands without interference with Native Americans who greatly limited expansion as they were now moved out of most of the land obtained from the Louisiana Purchase.
(McGraw Hill Topic 4)

Manifest Destiny

1845

This message from magazine editor John Louis O'Sullivan declared that it was the Americans God given right was to expand across the continent. This greatly contributed to the inevitability of expanding as Americans felt they were brought to America and born there by God with a purpose to spread their influence. The idea that the western lands were God given brought new life and resources showing its clarity to expansion of power and influence.
(McGraw Hill Lesson Topic 4 Lesson 7).

Mexican Cession

1848

This event was the outcome of the Mexican War over land. After the U.S. ultimately won the Mexican Cession was the product. It granted the U.S. California, Nevada, Utah, Arizona, and New Mexico. This gave the American people freedom to expand southwest without conflict with Mexico and the Native Americans and Mexicans who had already existed in these lands. This land obtained made it inevitable that people would expand, growing the size of the U.S.

The Dred Scott Decision

1857

The Supreme Court decided whether territories be free or not. The Southern majority was expected to rule in favor for slavery in their territories which did happen. This decision heightened the intensity between politics as the Supreme Court ruled that the federal government could not stop slavery in the territories and that limiting the expansion of slavery west was unconstitutional. This allowed pro-slavery people to travel freely with slaves during the westward expansion.
(6.2 Slavery)

Pacific Railroad Act

1862

This act gave two companies permission to build a trans-continental railroad. These railroads allowed for materials and people to be transported across the U.S. making it easier for people to expand further west as it connected Eastern states all the way to California. With easy access to the west and industrial growth it was inevitable for the U.S. to continue to grow and expand.
(McGraw Hill Topic 7 Lesson 9)