The United States had two significant territorial expansions after the Revolutionary War. In the Treaty of Paris of 1783, the United States got land from Great Britain. Our boundaries went beyond the boundaries of the thirteen colonies. We now controlled the land that extended westward to the Mississippi River, northward to what is now the border with Canada, and southward to Spanish Florida.

There were some issues that came with this territorial expansion. The first issue was the threat of attack by the Native Americans. The Native Americans feared our presence and attacked us often. We fought the Native Americans, and after defeating them in battle, they had to move west. For example, after winning the Battle of Fallen Timbers, the Native Americans had to give up land and move west. Another issue was organizing these lands that we received from Great Britain. The Land Ordinance of 1785 helped organize the western lands. The western land was divided into townships that were six miles wide and six miles long. Within each township were 36 squares. Land could be sold in most of these squares for $1.00 an acre.

The second major expansion occurred in 1803. We wanted to buy New Orleans and West Florida from France for $10 million so we could use the Mississippi River and the port of New Orleans. Napoleon countered our offer by asking us if we wanted to buy the entire Louisiana Territory for $15 million. We agreed, and we got most of the land west of the Mississippi River up to the Rocky Mountains and to the border with Canada. This purchase doubled the size of our country. When we gained this land, we needed to learn more about it. President Jefferson asked Lewis and Clark to explore the land and report on what they found. As a result of their explorations, we learned about the land, and maps of the region were developed. We also had some issues and conflicts with the Native Americans who lived in this region. The Native Americans weren't pleased to see us expand into this territory.

After the Revolutionary War, we expanded westward. The westward expansion presented challenges for us, which we were able to deal with and overcome.

How did the U.S. expand territorially after the Revolution, and what challenges arose?

How did the United States expand territorially after the American Revolution? It expanded from the original 13 colonies, all of which lied along the coast of the Atlantic Ocean, to the coast of the Pacific Ocean, a distance, depending upon precise starting and ending points, of around 3,000 miles. Those 13 colonies, in short, would eventually become the 48 contiguous United States, with Alaska and Hawaii added later to round-out the total at 50.

Following the Revolutionary War, the leaders of the newly-established United States of America set themselves on a course of expansion as a matter of economic and military necessity. The situation with the British Empire remained extremely tense (remember that the War of 1812 loomed ahead), and relations with France were increasingly uncertain as Napoleon Bonaparte embarked upon military expedition after military expedition. It was, in fact, France’s continued colonization of the Louisiana territory, and, particularly, the port of New Orleans, that served as one of the first and most important obstacles confronting the United States. Fortunately for then-President Thomas Jefferson, however, Napoleon was overextended and willing to sell France’s holdings, some of which had been held by Spain, to the United States. What became known as “the Louisiana Purchase” of 1803 doubled the physical size of the United States and gave America its sought-after port on the Mississippi River from which to export goods abroad while importing goods from foreign nations.

Beyond the expansion associated with the Louisiana Purchase, the policy of Manifest Destiny represented the other great expansion of the United States. The phrase coined by newspaper editor John O’Sullivan, an individual imbued with an exceptionally but hardly unique sense of divine providence with respect to his country’s destiny, wrote the following for publication in an 1839 issue of The United States Democratic Review:

“The expansive future is our arena, and for our history. We are entering on its untrodden space, with the truths of God in our minds, beneficent objects in our hearts, and with a clear conscience unsullied by the past. We are the nation of human progress, and who will, what can, set limits to our onward march? Providence is with us, and no earthly power can. We point to the everlasting truth on the first page of our national declaration, and we proclaim to the millions of other lands, that "the gates of hell" -- the powers of aristocracy and monarchy – ‘shall not prevail against it’."

O’Sullivan’s point was that the United States had a God-given right to expand its sovereignty over the lands as far as its abilities will allow. He would continue to advance the cause of American expansionism from Atlantic to Pacific coasts in his editorials, as in the following oft-cited passage from December 27, 1845:

"And that claim is by the right of our manifest destiny to overspread and to possess the whole of the continent which Providence has given us for the development of the great experiment of Liberty and federated self-government entrusted to us."

The policy, or concept, of Manifest Destiny, then, was used to legitimize the nation’s westward expansion, the charts for which were developed by Meriwether Lewis during his, and William Clark’s, government-sponsored expedition to explore the lands that lied beyond the country’s frontiers. The Lewis and Clark Expedition, in fact, had been commissioned with the eventual expansion of America’s initial frontiers already in mind.

The obstacles confronted by the United States during its westward expansion involved mainly opposition from British colonists in Canada, the initial colonization by Spain and France of the Louisiana territory, and, of course, the indigenous tribes that were already living in the lands that the United States was committed to conquer. It was the latter that presented the single greatest military obstacle to this expansion, although Mexico’s tenacity in defending the Texas territory was clearly no small thing. The series of treaties signed with these indigenous tribes, the Native Americans, and eventually violated by the United States, served to facilitate westward expansionism, but at the cost of those tribes’ cultures, lands, and dignity.