U.S. Westward Expansion, Treaties, and Immigration in 19th Century

Manifest Destiny

The 19th-century belief that the United States was destined to expand across the entire North American continent, from the Atlantic to the Pacific Ocean.

Land-hunger (background factor)

A long-standing American desire for more land, combined with a refusal to recognize Native American land rights or societies as legitimate, which made westward expansion politically and socially acceptable.

"Expand or die" mentality

The belief that in an imperialist world, nations must continuously expand their territory or risk being overtaken by rival powers — used to justify American expansionism.

Roberts Treaty (1833)

A trade agreement between the United States and Siam (modern-day Thailand), one of the early signs of American interest in Pacific trade routes.

First Opium War (1839-42)

A conflict in which Britain defeated China and forced open Chinese ports to trade. This alarmed American leaders, who feared Britain would dominate Pacific trade and shut the U.S. out.

Tyler's warning about Hawaiian Islands (1842)

President Tyler warned European powers not to interfere with Hawaii, signaling early U.S. interest in controlling Pacific trade routes.

Treaty of Wangxia (1844)

A treaty between the United States and China that gave the U.S. the same trading privileges Britain had won in the Opium War — an early step in American Pacific ambitions.

Oregon Territory

A large region in the Pacific Northwest (modern Oregon, Washington, and parts of Canada) that was claimed by both the United States and Britain, and was particularly important to northern expansionists due to its Pacific access.

49th Parallel

The line of latitude eventually agreed upon as the border between U.S. and British territory in the Pacific Northwest, dividing the Oregon Territory.

"54'40 or fight!"

A campaign slogan used by American expansionists demanding that the U.S. claim all of the Oregon Territory up to 54°40' north latitude, threatening war with Britain if necessary.

Republic of Texas (1836-1846)

An independent republic that broke away from Mexico in 1836 after the Texas Revolution. It was of special interest to southerners, who wanted to add it to the U.S. as a slave state.

Texan vote to accept U.S. annexation (1837)

After winning independence from Mexico, Texas voted to be annexed by the United States, but the request was repeatedly delayed due to political controversy over slavery.

President Van Buren rejects Texas

President Martin Van Buren refused to annex Texas, fearing it would provoke war with Mexico and inflame the debate over the expansion of slavery.

Tyler's Treaty of Annexation with Texas (1844)

President John Tyler negotiated a treaty to annex Texas, but the U.S. Senate refused to ratify it due to concerns about admitting another slave state.

John Slidell's Mission (September 1845)

President Polk sent diplomat John Slidell to Mexico to offer money for California and New Mexico, and to settle the Texas border dispute. Mexico refused to meet with him, helping push the two countries toward war.

Mexican-American War (1846-48)

A war between the U.S. and Mexico triggered by a dispute over the Texas border. The U.S. won decisively, gaining a massive amount of territory in the Southwest.

Wilmot Proviso (August 1846)

A proposed law that would have banned slavery in any territory gained from Mexico during the Mexican-American War. It passed the House but failed in the Senate, deepening the sectional divide over slavery.

Treaty of Guadalupe Hidalgo (1848)

The peace treaty ending the Mexican-American War. Mexico gave the U.S. over 500,000 square miles of territory (including California, New Mexico, and Arizona) in exchange for $15 million.

Buchanan-Pakenham Treaty / Oregon Treaty (June 1846)

The treaty between the U.S. and Britain that settled the Oregon boundary dispute at the 49th parallel, avoiding war and giving the U.S. the Pacific Northwest below that line.

Efforts to purchase Cuba

After the Mexican-American War, American expansionists — especially southerners — pushed to buy Cuba from Spain in order to add another potential slave state. Spain refused.

Efforts to purchase more land from Mexico

The Gadsden Purchase (1853) was a later attempt to buy additional land from Mexico, motivated by the desire to build a southern transcontinental railroad route.

Push factors

Conditions in a home country that drive people to emigrate, such as famine, poverty, political persecution, or lack of economic opportunity.

Pull factors

Conditions in a destination country that attract immigrants, such as available land, higher wages, political freedom, or job opportunities.

Net migration

The difference between the number of people entering and leaving a country. A positive net migration means more people are arriving than leaving.

"First Great Wave" of immigration

The large surge of immigration to the United States in the 1840s and 1850s, primarily from Ireland and Germany, which dramatically changed the country's demographics.

Demographic transition in Europe

In the 19th century, European death rates fell faster than birth rates, causing rapid population growth and resulting in land shortages and unemployment that pushed people to emigrate.

Decline of feudal restrictions

As the old feudal system broke down in Europe, rural peasants were displaced from the land they had farmed for generations, leaving them without stable livelihoods and prompting emigration.

Irish Potato Famine

A catastrophic crop failure in Ireland from 1845 to 1852 caused by potato blight, which led to mass starvation and the death or emigration of roughly 2 million Irish people.

Failed 1848 political revolutions

A wave of revolutions swept across Europe in 1848, demanding democracy and liberal reform. When most of these revolutions failed, political activists and reformers — especially Germans — fled to the U.S. to escape persecution.

Poor harvests in Germany

Agricultural failures in the German states in the 1840s worsened economic conditions for rural Germans, contributing to the decision to emigrate.

Industrialization

The rapid growth of American factories and cities in the 1840s-1850s created a demand for cheap labor, attracting immigrants seeking work.

California Gold Rush

The discovery of gold in California in 1848 drew hundreds of thousands of people to the American West, including many immigrants, seeking fortune.

Trans-Atlantic steamship service

The introduction of steam-powered ships in the mid-19th century made the Atlantic crossing faster, cheaper, and safer, making emigration more accessible for ordinary Europeans.

High return migration rate

Unlike later waves of immigrants, a relatively high proportion of those who came during the first great wave eventually returned to their home countries, suggesting some saw the move as temporary.

Irish immigrants

The first large group of primarily urban immigrants in the U.S. Many arrived desperately poor, having traveled in cargo ships (not passenger ships). They settled in northeastern cities like New York and Boston, and over time built political influence through machine politics and voting blocs.

German immigrants

Settled primarily in the Midwest (e.g., Missouri, Wisconsin, Ohio). Many were politically active and focused on events back in Germany. The "48ers" — refugees from the failed 1848 revolutions — were particularly influential, bringing liberal and anti-slavery views.

Chinese immigrants

Often considered part of a second great wave. Came primarily to the West Coast, drawn by the Gold Rush and later railroad construction. Immigration peaked in the 1870s before facing severe legal restrictions.

Nativist resentment

A hostile reaction by native-born Americans to the surge of immigration, driven by fears that immigrants would take jobs, undermine Protestant culture, or bring radical politics.

Anti-Catholic prejudice

Many native-born Protestant Americans viewed the large numbers of Irish and German Catholic immigrants with suspicion and hostility, fearing Catholic loyalty to the Pope over American democracy.

Anti-alcohol sentiment

Some nativists associated German immigrants with beer-drinking culture and feared they would spread habits considered immoral by Protestant temperance advocates.

Anti-socialism / anti-48ers

Some Americans feared the radical political ideas brought by German immigrants who had participated in the 1848 revolutions, including socialism and anti-Church secularism.

Anti-Chinese sentiment (nativism)

Widespread hostility toward Chinese immigrants, particularly in California, often fueled by economic competition for jobs. Notably, some of this hostility came from other immigrant groups, not just native-born Americans.

Know Nothings / Order of the Star-Spangled Banner (OSSB)

A secretive nativist fraternal organization formed in the early 1850s. Members were instructed to say "I know nothing" if asked about the group. They were strongly anti-Catholic and anti-immigrant.

American Party

The political party that grew out of the Know Nothing movement. It had significant electoral success in the mid-1850s before collapsing over the issue of slavery.

Decline of the American Party

The American Party fell apart in the late 1850s because it could not hold together its coalition once the slavery debate became the dominant political issue, and many of its members shifted to the new Republican Party.

Western land rush after Treaty of Guadalupe Hidalgo

After the Mexican-American War, there was rapid, large-scale migration: southerners poured into Texas, New Mexico, and Arizona, while northerners flooded into California.

Slavery in newly acquired territories

The core question after the Mexican-American War: would the new western territories become free or slave states? This threatened the balance of power in the U.S. Senate between free and slave states.

Senate balance of "free soil" and "slave soil"

The U.S. Senate was carefully balanced between free and slave states since each state had two senators. Adding new states would tip the balance, making the status of new territories a matter of intense political conflict.

Wilmot Proviso (failed)

A proposed law that aimed to ban slavery in any territory gained from the Mexican-American War. It passed the House but failed in the Senate, leaving the question of slavery in the new territories unresolved.

Popular sovereignty

The idea that the people living in a new territory should vote to decide whether it would allow slavery, rather than having Congress decide. Promoted by Stephen Douglas as a compromise.

Missouri Compromise

An 1820 law that stated there had to be a balance between free and slave states, and that slavery would be prohibited in territories north of the 36°30' line (except Missouri).

Free Soil Party

A political party that advocated for banning the expansion of slavery into new western territories, though it did not necessarily call for abolishing slavery where it already existed.

Compromise of 1850

A series of laws passed in August 1850 designed to resolve the crisis over slavery in the territories acquired from Mexico. Key components included California's admission as a free state, the creation of New Mexico Territory, Texas debt relief, and the Fugitive Slave Act.

California statehood (1850)

California was admitted to the Union as a free state under the Compromise of 1850, disrupting the balance of free and slave states in the Senate.

New Mexico Territory

Created by the Compromise of 1850 from parts of Texas, in hopes that it might eventually become a slave state and restore the Senate balance.

Texas trades territory for debt relief

Under the Compromise of 1850, Texas gave up disputed land claims in New Mexico in exchange for the federal government assuming Texas's public debt.

Fugitive Slave Act (1850)

Required that escaped enslaved people be returned to their enslavers even if found in free states. It also punished anyone who helped enslaved people escape. This deeply angered northern abolitionists.

Uncle Tom's Cabin (1851-52)

A novel by Harriet Beecher Stowe told from the perspective of enslaved people. It depicted the brutal realities of slavery and dramatically increased anti-slavery sentiment in the North. Often called the book that made the issue of slavery so pressing.

Kansas-Nebraska Act (May 1854)

A law that created the Kansas and Nebraska territories and allowed their residents to decide the slavery question through popular sovereignty, effectively repealing the Missouri Compromise.

"Bleeding Kansas" (1854-59)

A period of intense political violence in Kansas as pro-slavery and anti-slavery settlers flooded in to influence the vote on slavery. It became a preview of the coming Civil War.

"Border ruffians"

Pro-slavery militants, mostly from Missouri, who crossed into Kansas to vote illegally and intimidate anti-slavery settlers during the Bleeding Kansas period.

Rep. Preston Brooks attacks Sen. Charles Sumner (May 1856)

Senator Sumner gave a speech harshly condemning slavery and pro-slavery forces. In response, Representative Preston Brooks of South Carolina beat him severely over the head with a metal-tipped cane on the Senate floor.

Violence in Lawrence and Pottawatomie

Pro-slavery forces sacked the anti-slavery town of Lawrence, Kansas. In retaliation, abolitionist John Brown led the Pottawatomie Massacre, killing five pro-slavery settlers.

Lecompton Constitution (1857)

A proposed pro-slavery state constitution for Kansas, widely seen as fraudulent and unfair. Its national controversy deepened the split within the Democratic Party.

Wyandotte Constitution (1859)

A free-soil constitution proposed for Kansas. Neither it nor the Lecompton Constitution was ultimately passed before the Civil War.

Formation of Republican Party (Summer 1854)

A new political party formed in response to the Kansas-Nebraska Act, bringing together anti-slavery Whigs, Free Soilers, and northern Democrats. It was pro-business and pro-free labor, and made no effort to build a southern base.

Election of James Buchanan (1856)

Buchanan, a Pennsylvania Democrat, won the presidency. He was seen by some as a moderate who could preserve the Union, but critics said he was weak and unwilling to take a stand against the growing sectional crisis.

Dred Scott v. Sandford (1857)

A Supreme Court case in which Chief Justice Roger Taney ruled that enslaved people were not citizens, had no right to sue in federal court, and that Congress had no power to ban slavery in any territory. He declared the Missouri Compromise unconstitutional, effectively opening all territories to slavery.

Lincoln's "House Divided" speech (June 1858)

A famous speech in which Lincoln argued that the U.S. could not survive permanently half slave and half free — it would eventually become all one or all the other. He rejected both the Missouri Compromise and popular sovereignty as long-term solutions.

John Brown's raid on Harpers Ferry (October 1859)

Radical abolitionist John Brown led a raid on a federal armory in Harpers Ferry, Virginia, hoping to seize weapons and inspire a slave uprising. The raid failed; Brown was captured, tried, and hanged. It terrified the South and deepened sectional tensions.

Failure of Democrats to unify (1860)

The Democratic Party split in 1860, with northern Democrats nominating Stephen Douglas and southern Democrats nominating John Breckinridge, effectively handing the election to the Republican Lincoln.

Republican platform (1860)

The Republicans ran on a platform opposing the expansion of slavery into new territories, supporting protective tariffs, and promoting free land for settlers (Homestead Act). They did not call for abolishing slavery where it already existed.

1860 Election

Abraham Lincoln won the presidency with no electoral votes from the South. His election triggered the secession of southern states, as southerners feared he would end the expansion of slavery.

Secession of the southern states

Seven states (later eleven) seceded from the Union after Lincoln's election, starting with South Carolina. They argued that states had the right to leave the Union if their interests were threatened.

Confederate States of America

The government formed by the seceding southern states. Its constitution was similar to the U.S. Constitution but explicitly protected slavery and gave states more power. It was never recognized as a legitimate country by any major foreign power.

Lincoln's inauguration

Lincoln had to be secretly transported to Washington D.C. due to credible assassination threats — a sign of how deeply divided and volatile the country had become.

Attack on Fort Sumter (April 1861)

Confederate forces attacked the Union-held fort in Charleston Harbor, South Carolina, starting the Civil War. Almost no one died, but it was seen as a strategic blunder by the Confederacy because it unified Northern public opinion against them.

Lincoln's mobilization of state militia

After Fort Sumter, Lincoln called 75,000 state militia troops into service and announced a naval blockade of the South, beginning the Union's war effort.

Secession of four more states

After Lincoln called for troops, four more states (Virginia, Arkansas, Tennessee, and North Carolina) seceded. Virginia's secession caused the western pro-Union counties to split off and form West Virginia.

European relations with the USA and CSA

Both sides tried to win European support. The Confederacy hoped Britain and France would intervene due to their need for Southern cotton; the Union worked to prevent this.

Confederate cotton embargo

The Confederacy unilaterally stopped exporting cotton, hoping to create a "cotton famine" in Britain and France that would force them to recognize the Confederacy. The strategy failed — Europe found other cotton sources.

Economic advantages of the North

The North had a larger population, more factories, more miles of railroad, a stronger banking system, and a functioning navy — all of which gave it major strategic advantages.

Defensive advantages of the South

The South only needed to defend its territory rather than conquer the North. It knew the land better, had strong military leaders like Robert E. Lee, and soldiers were highly motivated to defend their homes and way of life.

"Anaconda Plan"

Union General Winfield Scott's strategy to defeat the Confederacy: (1) blockade Southern ports to strangle the economy, and (2) seize the Mississippi River to split the Confederacy into three pieces.

Slidell-Mason Affair

Confederate diplomats James Mason and John Slidell were seized by the Union Navy from a British ship. Britain was furious and nearly went to war with the Union, but tensions eased after the diplomats were released.

Confiscation Acts (1861-62)

Laws passed by Congress allowing the Union to seize Confederate property, including enslaved people who were used in the Confederate war effort. Lincoln was cautious about full emancipation due to concerns about border state loyalty.

Lincoln's concern over border states

The border states (Missouri, Kentucky, Maryland, Delaware) were slave states that had not seceded. Lincoln was careful not to push them into the Confederacy by moving too aggressively against slavery.

Emancipation Proclamation (September 1862)

Lincoln's executive order declaring that all enslaved people in Confederate-held territory were free. It did not immediately free anyone (it only applied where the Union had no control), but it reframed the war as a fight against slavery, discouraged European support for the South, and allowed Black men to enlist in the Union Army.

Battle of Antietam (September 1862)

The bloodiest single day of the Civil War. A Union tactical victory that stopped Lee's first invasion of the North and gave Lincoln the opportunity to issue the Emancipation Proclamation.

Battle of Gettysburg (July 1863)

A major Union victory in Pennsylvania that stopped Lee's second invasion of the North. Considered the turning point of the Civil War in the Eastern Theater.

Failures of the Army of the Potomac (1861-63)

The main Union army in the East repeatedly failed to defeat Lee's Army of Northern Virginia, going through a series of incompetent commanders before Grant took command.

Union successes in the West

While the East stagnated, Union forces in the West captured New Orleans and pushed down the Mississippi River, making progress on the Anaconda Plan.

Immense costs of the war

The Civil War was enormously costly in lives and money for both sides, but the South suffered more proportionally due to its smaller population, less developed economy, and the war being fought mostly on Southern soil.

Tariff increases

The Republican Congress raised tariffs on manufactured goods to generate revenue for the war and protect Northern industry — a long-standing Republican economic priority.

Homestead Act (May 1862)

Gave 160 acres of western land to settlers who would farm it for five years. It aimed to encourage free-soil settlement in the West and was explicitly denied to Confederate citizens.

Pacific Railway Act (July 1862)

Authorized the construction of a transcontinental railroad, linking the East and West coasts to boost trade, settlement, and military logistics.

National Banking Act (February 1863)

Allowed banks to operate across state lines and created nationally chartered banks supervised by the U.S. Treasury. Before this, bank notes were only accepted in the state where they were issued.

"Greenbacks"

Paper currency issued by the Union government, backed by government debt (IOUs) rather than gold or silver. They were used to finance the war but caused inflation.

Confederate economic weaknesses

The Confederacy had a smaller tax base, less creditworthiness, fewer factories, and relied heavily on printing money to fund the war, leading to devastating inflation.

Suspension of rights to jury trial

Both the Union and the Confederacy suspended the right to jury trial (habeas corpus) during the war to deal with dissent and suspected spies — a controversial wartime measure on both sides.