Why Was the Louisiana Purchase Important?

Important Louisiana Purchase

At the turn of the 19th century the United States signed a treaty with massive ramifications. Just why was the Louisiana Purchase important and what impact did it have on the United States?

The Louisiana Purchase was a significant treaty in 1803 where the United States purchased the entire Louisiana territory from France for $15 million.

For roughly 3-4 cents per acre, the United States added over 828,000 square miles of territory, nearly doubling the size of the nation.

Perhaps most significantly, the Louisiana Purchase gave the United States possession of the important port city of New Orleans. New Orleans was vital to the economies of the western states and territories as it provided a cheaper route to global markets.

While the purchase is widely celebrated in the modern day, it faced significant backlash from Federalists over its constitutionality. The framers of the Constitution did not anticipate such a territorial extension to the United States.

President Thomas Jefferson himself deeply contemplated the purchase, particularly as it flew in the face of his cherished Jeffersonian ideals.

After heated debate, Congress ratified the treaty in 1803 and in turn, completely changed the trajectory of the nation.

Why did Thomas Jefferson buy the Louisiana Territory?

An interesting fact regarding the Louisiana Purchase is that Thomas Jefferson did not originally intend to buy the Louisiana Territory. His original intent was to only buy the port city of New Orleans.

Given its location at the mouth of the Mississippi River, New Orleans was critical for the economy. Western farmers utilized the Mississippi River to ship their goods south to access global markets.

Overland routes to the east were far more costly and dangerous.

The United States recognized how critical the city was to its economy and thus negotiated Pinckney’s Treaty with Spain in 1795 to ensure frontier farmers had access to the city.

After an October 1802 incident where Spanish authorities temporarily revoked US access to New Orleans, President Jefferson authorized Robert Livingston and James Monroe to negotiate the purchase of New Orleans.1

Signing of Louisiana Purchase
Depiction of Monroe and Livingston signing the Louisiana Purchase via NYPL

As Spain secretly transferred the Louisiana territory to France in 1800, Monroe and Livingston treated with the French.

French emperor Napoleon Bonaparte surprised the American diplomats by instead offering the entirety of the Louisiana territory. There were many reasons Napoleon sold the Louisiana territory, but once he made his decision, the sale was expected to be completed.

Although the offer exceeded their authority, Monroe and Livingston quickly negotiated and signed the treaty, obtaining Louisiana for $15 million.

When news reached the United States of the treaty, Jefferson faced a difficult decision.

Perhaps no one knew more so than Jefferson, a Francophile, the threat that France could pose on the western flank of the United States. The acquisition of the territory would secure US interests in the region. Jefferson also envisioned an expansion of the republic and the plentiful land that could feed his ideal agrarian economy. 

While he had doubts over the constitutionality of the purchase, Jefferson ultimately believed it was in the best interest of the nation to buy the Louisiana territory.

Why was the Louisiana Purchase Important?

The Louisiana Purchase was historically important as it scored Jefferson an economic and political victory, raised and answered constitutional questions, helped divide the Union and expand slavery, as well as decimated the Native American population.

Few treaties have led to a greater impact throughout the history of the United States. Without the territory acquired through the purchase, it is doubtful the United States would resemble anything close to what it does in the present day.

Theodore Roosevelt commented on the 100th anniversary of the purchase:

“The event which more than any other, after the foundation of the Government and always excepting its preservation, determined the character of our national life.”2

Alternatively, the Louisiana Purchase also helped to highlight the divisions within the United States and helped to spur the nation along a path towards the Civil War.

Louisiana Purchase important chart

Economic and Political Victory

A major reason the Louisiana Purchase was important was how it scored an economic and political victory for Thomas Jefferson.

The treaty was a defining moment of Jefferson’s presidency, one that would be marred in its later years by the Chesapeake-Leopard affair and detrimental effects of the Embargo Act of 1807.

Purchasing New Orleans and the Louisiana territory gave the United States complete control over the Mississippi River. Farmers no longer had to rely on the whims of a foreign nation to ensure their goods and produce could access global markets.

Louisiana Purchase map
Map of the Louisiana Purchase via LOC

Furthermore, the territory included in the purchase was vast—so vast in fact that it doubled the size of the United States. The land was arable and rich in natural resources—the ideal situation for a nation seeking to expand.

In Jefferson’s trademark eloquent style he quipped:

“... the fertility of the country, its climate and extent, promise in due season important aids to our treasury, an ample provision for our posterity, and a wide-spread field for the blessings of freedom and equal laws.”

Few American/European settlements existed beyond the Mississippi River at the time, with frontiersmen and trappers engaging in the fur trade as the primary Euro-American inhabitants.

Soon after the purchase Jefferson commissioned the Lewis and Clark Expedition to further explore and map the territory. The reports the group brought back captivated the nation and sparked further interest in westward expansion.

President Jefferson truly believed the Louisiana territory could ultimately help the United States to grow and spread its particular brand of democracy and liberty. Rather than a detriment, he envisioned the Mississippi River as holding the nation together.

It cannot be understated the criticality of owning New Orleans to help secure against British and French threats to the west. France very plausibly could have challenged the US with a significant force stationed in New Orleans.3

Raised and Answered Constitutional Questions

The Louisiana Purchase faced serious questions over its constitutionality, but it ultimately showed that the federal republic could survive a major constitutional challenge.

The ability to buy land from foreign nations was not a power explicitly written in the Constitution for the federal government. Jefferson’s Federalist opponents latched onto this interpretation, stating that Jefferson did not have the power to purchase the land and the attempt was a gross expansion of federal powers.

Ironically, the Federalists and the Jeffersonian Democrats flip-flopped their usual positions in regards to the Louisiana Purchase. Usually in favor of the expansion of federal power, the Federalists strongly opposed the purchase.

US Territory Expansion With Louisiana Purchase

The treaty also flew in the face of Jefferson’s strict constructionist view of the Constitution. He personally believed that a constitutional amendment would be necessary to authorize the powers.

Jefferson’s cabinet, including Treasury Secretary Albert Gallatin, rejected his notion of a constitutional amendment and assured him that any deal was permissible under the Constitution’s treaty-making provisions.

As the treaty could not wait for a constitutional amendment to pass, Jefferson proceeded with the purchase, stating:

“In the meantime we must ratify and pay our money, as we have treated, for a thing beyond the Constitution, and rely on the nation to sanction an act done for its great good, without its previous authority,”4

The debate on the Senate floor over the treaty’s ratification was contentious. Several Federalist members even threatened secession, though ultimately the Senate ratified the Louisiana Purchase with a 24-7 vote, well exceeding the two-thirds majority required.

Though some Federalists truly believed the treaty to be unconstitutional, it was never challenged in courts.

Helped Divide Union and Expand Slavery

Another important result of the Louisiana Purchase is how it helped to further divide the Union and expand the institution of slavery in the process.

Sectional tensions already featured prominently at the time of the Louisiana Purchase. The bitter election of 1800 showcased the prominent partisan divide, largely along sectional boundaries.

New Englanders already disliked that vast amount of land already available within the current boundaries of the United States. They often complained that the widely-available land depressed land prices and drove up wages in the East as laborers fled west to purchase cheap land.2

Bleeding Kansas expansion of slavery
Depiction of “Bleeding Kansas”—the event that occurred as the north and south fought over slavery in the Louisiana territories via Wikimedia

Northerners in general feared the implications of additional land and territory to the United States. New territory would lead to new states and thus diluted political power for the interests of the merchant-based New England states.

Senator Uriah Tracey from Connecticut perhaps said it best in regards to the Louisiana Purchase:

“This, would be absorbing the Northern states and rendering them as insignificant to the Union as they ought to be, if, by their own consent, the measure should be adopted.”3

Furthermore, northerners in particular feared the expansion of slavery into the territories. The invention of the cotton gin helped to revolutionize the cotton industry and exponentially spread cotton plantations across the south.

The fertile lands included in the Louisiana Purchase could easily support the expansion of slavery and thus southern political ambitions.

The contentious issue over slavery and what to do with the Louisiana territory would not be decided until the important Missouri Compromise of 1820.

Led to Further Demise of Native Americans

An often overlooked result of the Louisiana Purchase is how it helped further lead to the demise of Native Americans across the continent.

As was customary at the time, Native Americans and their wishes were completely ignored during the entire treaty process. In fact, it is doubtful that any natives living in the Louisiana territory were even aware that “possession” of the lands had once once again changed hands.

Many Americans at the time believed that the United States was already lush with available land east of the Mississippi River. President Jefferson knew that at the rapid clip of settlement, the US would be out of available land within a few generations.2

The Louisiana Purchase was therefore necessary to continue the spread of American liberty across the continent, whether wanted or unwanted by those already living there.

Plains Native Americans
Depiction of Plains Native Americans who had lived in the Louisiana territory for thousands of years via Wikimedia

While the Louisiana territory was often described as vast, untouched wilderness, thousands of natives across hundreds of nations were already living on the land.

As was the case for lands east of the Mississippi River, the federal government paid little mind to native lands when handing out cheap parcels of land to settlers. The scores of settlers that headed west across the next century predictably led to conflict, violence, and war.

Natives were wiped out entirely, or signed treaties ceding their lands and forcing them onto reservations that were nevertheless broken by the federal government.

The United States even utilized the new territory to forcibly relocate eastern Native American nations such as the Five Civilized Tribes with the Indian Removal Act of 1830.

The further subjugation of Native Americans left a stain upon the important Louisiana Purchase.


To recap, the Louisiana Purchase of 1803 was important for the following reasons:

  1. An economic and political victory for Jefferson
  2. Raised and answered constitutional questions
  3. Helped further divide the Union and expand slavery
  4. Led to the further demise of Native Americans

The trajectory of the United States was forever changed the moment the nation nearly doubled in size.

The purchase would go on to have profound political, social, and economic consequences for the fledgling young nation.

Before those ramifications would be realized, the United States had other significant world events to navigate. British impressment of American sailors threatened its sovereignty and the looming War of 1812 nearly fractured the nation at its seams.

While the Era of Good Feelings provided a temporary reprieve from the sectional infighting, the different opinions over the role of slavery, sectional interests, and political ideology constantly threatened the United States.

Despite its important role in expanding the United States, the Louisiana Purchase inevitably helped lead the United States to its fateful Civil War.


To learn more about US history, check out this timeline of the history of the United States.


1) Hemphill, W. Edwin. “The Jeffersonian Background of the Louisiana Purchase.” The Mississippi Valley Historical Review, vol. 22, no. 2, 1935, pp. 177–90. JSTOR, https://doi.org/10.2307/1898465.

2) Onuf, Peter S. “The Revolution of 1803.” The Wilson Quarterly (1976-), vol. 27, no. 1, 2003, pp. 22–29. JSTOR, http://www.jstor.org/stable/40260700.

3) Sloane, William M. “The World Aspects of the Louisiana Purchase.” The American Historical Review, vol. 9, no. 3, 1904, pp. 507–21. JSTOR, https://doi.org/10.2307/1833473.

4) Deutsch, Eberhard P. “The Constitutional Controversy Over the Louisiana Purchase.” American Bar Association Journal, vol. 53, no. 1, 1967, pp. 50–57. JSTOR, http://www.jstor.org/stable/25723883.

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