The rush westward in America was filled with excitement, wonder, and opportunity for many people that wanted to leave and start a new life. During this time period, people packed up their belongings and would set out to find a new home that better suit their wants and needs, whether this be physically or politically. With all this growth, new states were forming very quickly, and the question of slavery came with it. Territories such as Texas, California, Kansas, Missouri, and Nebraska were all forced to make the choice of allowing slavery or not and ultimately the fate of the country. Proslavery supporters along with abolitionists flocked to these states to sway political policy throughout the country. This push for or against slavery had profound impacts on national politics which would further divide the country. The first half of the 19th century in the United States was filled with tension which kept the idea of slavery at the forefront of news and politics. The westward expansion period brought about more than just the idea of new lands and new lives, it brought about one of the most controversial arguments in this nation’s history and even more division than previously imagined.

Map showing spread of slavery in the United States from 1790-1860, Lincoln Mullen, “The Spread of U.S. Slavery, 1790–1860,” interactive map,,doi:0.5281/zenodo.9825.

Looking at this idea of slavery and westward expansion can interest many people from seasoned historians to average history buffs as it encompasses so much of our nation’s history at a very important time. The 19th century saw much of our growth as a nation, with 18 new states being added from 1800 to 1861, which brought with it much political and social change. This time in our past contains many events and people that are iconic to American history and should be examined by everyone that takes interest as it is a very intriguing time.

Map showing the percentage of slaves in Texas, “Black Slaves as a Percentage of Total Population, 1860.” Texas State Historical Association ,

The debate over slavery existing in newly formed states during the period of westward expansion in the US further drove the country apart and was an underlying cause of the Civil War. Slavery and westward expansion went hand and hand during the first half of the 19th century because every newly formed state was forced to make the same choice, to allow slavery or not. Supporters on both sides were eager to relocate to new lands and spread their opinions and sway the state to one side or the other which led to events like bleeding Kansas. Westward expansion was occurring during the peak of slavery and new states were seeing huge migrations of people from all over to settle. This created political battlegrounds where both proslavery and abolitionists fought for what they believed was right. Proslavery supporters were fighting not just for what they called their way of life, but for the massive amount of profit free labor produced. Their push to expand slavery west was one purely aimed at increasing profit and maximizing revenue. In the article “Jefferson Davis and Proslavery vision of empire in the Far West” by Kevin Waite, he argues that the drive to expand slavery westward was mainly for financial gain. He claims, “Davis suggested, there were natural incentives for the expansion of slavery” and that even if the climate would not allow for the growing of cash crops such as cotton or sugar, that slaves could be used in the mining industry in the search for gold and silver that had already been found in some newly formed western states.[i] Abolitionist knew that the only way to keep slavery confined to the southeast was to pass legislature that would prohibit slavery in these new states so the push to migrate to these new areas became extremely important to their cause as well. Slavery and western expansion occurred at a pivotal time in our nation’s history and would alter it for centuries to come. 

U.S. expansion west and each states stance on slavery, User Golbez. “US Slave and Free States 1789-1861.” Wikimedia Commons, 14 Feb. 2009,

The first half of the 1800’s saw an enormous amount of division and confrontation between the two sides of the slavery debate and if it would exist in the west. To understand the mood of the country at this time, one must know which states were newly admitted to the union and their stance on slavery. Places such as Texas, California, and Kansas were heavily disputed weather they would allow slavery or not. 18 states were added in the 1800’s before the Civil War took place and each one tipped the scales in the battle of slavery. In 1800, the number of slave states to free states was in favor of the south 9 to 8. This would change in 1820 with the Missouri Compromise evening the number at 12 for each side divided at the 36° 30° latitude line. The scales would continuously be balanced until 1850 when the addition of California. Northern Democrats feared that with the U.S. winning the Mexican American war, the addition of new territory coming as a result could tip the balance in favor of the south. Then president James K. Polk negotiated around 31,000 acres of land from Mexico for $10 million that became known as the Gadsden Purchase which along with the land already gained from the war would give slaveholders an advantage in the senate. This advantage would pay off very well as it helped to stop the Wilmot Proviso, which was designed to eliminate slavery in the lands acquired from the Mexican Cession and the Gadsden Purchase. After this period of expansion that saw the country more than double in size, proslavery supporters and abolitionists flocked to the new territories to sway politicians. 

Political cartoon from the 1800’s,  Magee, J.L. Forcing slavery down the throat of a freesoiler. 1865. Library of Congress, Washington D.C.     

The pull of the wild west drove many people to venture out for themselves. Amazing views, open land, and opportunity is what most went for, but some also went to fight for what they viewed as right. Both proslavery supporters as well as abolitionists came in droves to new territories as a race ensued to see if the state would be free or allow slavery. Slavery was not the only thing making pack their belongs and head west. Gold was found in the California territory and the gold rush began. Many saw this as a way to get rich quickly and create a new life for themselves. The gold rush attracted slaveholders in the south who looked to use their free labor system in the mining industry. Land was being given away in the west and southern planters were eager to see if they could continue their way of life in this new environment. Another reason people were going west is because of the new advancements in transportation technology. The push for a rail line from the Atlantic to the Pacific was growing by the day and both north and south wanted the line to go through their own states. The completion of a transcontinental rail line would provide people a much easier way to migrate west and populate these new territories. Stopping or continuing the advancement of slavery west was not the only driving factor in people moving to these territories but it was one of the main concerns when they reached their destination.

An overview of U.S. western expansion and the compromises that came about, Khanacademy, director. Slavery and Missouri Compromise in Early 1800s | US History | Khan Academy. YouTube, YouTube, 10 Sept. 2015,

The expansion of America westward was a heated topic in the political world as both sides were looking to lay claim to as many states as they could to help support their cause. The first attempt of solving the problem with slavery in the west was the Compromise of 1820, also known as the Missouri Compromise. This bill allowed for Missouri to be admitted into the union as a slave state while Maine would be a free state. The bill also band slavery in the rest of the territory acquired from the Louisiana Purchase. The Missouri Compromise would ease some tension in the still ever-growing divide of our country but will be shifted in the next decades. The Compromise of 1850 was crafted by Kentucky senator Henry Clay to try and fix the problem of slavery in the west. The compromise called for the admittance of California into the union as a free state, established Utah and New Mexico as territories that could decide via popular sovereignty if they would permit slavery, and passed the Fugitive Slave Act. This was band aid to a larger problem that would come about in the coming years.

We cross the prairie as of old

the pilgrims crossed the sea,

to make the West, as they the East,

The homestead of the free!

We go to rear a wall of men

On Freedom's southern line,

and plant beside the cotton-tree

the rugged Northern pine!

We're flowing from our native hills

As our free rivers flow:

The blessing of our Mother-land

Is on us as we go.

We go to plant her common schools

On distant prairie swells,

and give the Sabbaths of the wild

The music of her bells.

Upbearing, like the Ark of old,

The Bible in our van,

We go to test the truth of God

Against the fraud of man.

No pause, nor rest, save where the streams

that feed the Kansas run,

Save where our Pilgrim gonfalon

Shall flout the setting sun!

We'll tread the prairie as of old

Our fathers sailed the sea,

and make the West, as they the East,

The homestead of the free!

A Poem written by John Greenleaf Whittier supporting the abolitionists that moved to Kansas, Whittier, John Greenleaf. “John Greenleaf Whittier: The Kansas Emigrants.” In Gale U.S. History Online Collection. Detroit, MI: Gale, 2015. Gale In Context: U.S. History (accessed April 22, 2021).

 In 1854, the Kansas-Nebraska Act was passed, which created the new territories of Kansas and Nebraska and would allow them to choose to allow slavery or not based on popular sovereignty. These bills would set the stage for an event that would become known as Bleeding Kansas. Settlers from both north and south went to Kansas to try and establish dominance over the region for their cause. The idea of popular sovereignty was thought to eliminate the sectional divide between north and south by letting the people of the state chose to allow slavery or not. Over the course of 5 years, from 1855 to 1860, fifty-five people were killed in the struggle for Kansas. After a fierce battle both physically and politically, Kansas was admitted into the union as a free state after the secession of confederate states, just 3 months before the outbreak of the Civil War. This conflict in Kansas was the last straw and would light the powder keg that would become the American Civil War.

Breakdown of the Kansas-Nebraska Act, TEDEducation, director. How One Piece of Legislation Divided a Nation – Ben Labaree, Jr. YouTube, YouTube, 11 Feb. 2014,

The 1800’s saw much of our growth as a nation, both in size as well as our passion for what we believed in. The decision to move west by both north and south had a profound impact on this country’s history and altered the lives of many. Slavery had divided the country since before we became independent, and the era of western expansion only drove this division farther. New territories that were becoming states were all forced to make the choice of slavery or not. Politics played a major role in the state’s choice and the laws that controlled slaves’ lives. The fight for not only land, but political control of the national government and if slavery would exist outside of the southeast. This turmoil created around slavery and western expansion would fuel the fire and eventually become the American Civil War.

[i] Waite, Kevin. “Jefferson Davis and proslavery visions of empire in the Far West.” The Journal of Civil War Era 6, no. 4 (2016): 536+. Gale In Context: U.S. History (accessed April 22, 2021).

How to cite this article

David Geney, “The Spread of Slavery and Western Expansion in the United States,” Digital History at USC Aiken, 2021.

Further Readings

Foner, Eric. Politics and Ideology in the Age of the Civil War. Oxford University Press, 1980. Editors. “Bleeding Kansas.”, A&E Television Networks, 27 Oct. 2009,

“Missouri Compromise Ushers in New Era for the Senate.” U.S. Senate: Missouri Compromise Ushers in New Era for the Senate, 24 Mar. 2020,

“The Kansas-Nebraska Act.” U.S. Senate: The Kansas-Nebraska Act, 12 Dec. 2019,,territories%20to%20sway%20the%20vote.

“The Kansas Question–Submission of the Constitution to the Popular Vote.” 1857.New York Times (1857-1922), Nov 09, 2.

2 thoughts on “The Spread of Slavery and Westward Expansion in the United States

  1. David, this is a very informative article! Your article does an excellent job of contextualizing westward expansion and explaining the political division that was prevalent in the nineteenth century. Additionally, your inclusion of maps that depict westward expansion and the spread of slavery made the article very effective. I thought that the Whittier poem was an excellent addition as well.


  2. David, this is a great, well written article. I think you did an excellent job using maps as well. Very intriguing article.


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