Chapter 9: Expansion Leads to Conflict

Big Picture: Between 1830 and 1860
Americans by the thousands
migrated westward into the frontier
wilderness. In 1846, souring relations
led to war between Mexico and the
United States, and the outcome
defined America’s borders.
Main Idea: Americans in large
numbers followed trails to the
West in the 1840s and 1850s
Americans Head West
Manifest Destiny
Reasons to Migrate West
• Population and size of country
grew rapidly by the 1840s
• Many Americans believed the
idea that the nation had a Godgiven right to all of North
• Little thought was given to the
impact on others of this belief
• Believed in manifest destiny
• Mountain men went to trap and
• Missionaries hoped to convert
Native Americans to Christianity
• Lumberjacks and miners went
to capitalize on natural
• Farmers moved for vast, rich
• Entrepreneurs knew if they
were first to set up shop the
greater their chance for success
Major Western Trails
The Santa Fe Trail
The Oregon Trail
• 1st major western trail
• 800-miles from Independence,
MO to Santa Fe, NM
• Began as a trade route
• By the 1840s, it served as a
route for migrants heading
• Longest and most famous
• 2,000-miles from
Independence, MO to
Willamette Valley in OR
• Parts of it used by Native
Americans for centuries, Lewis
and Clark used parts on their
expedition, along with fur
traders and mountain men
• By the 1840s it was established
as a major trail west
The Mormon Trail
• 1830, Joseph Smith founded
the Church of Jesus Christ of
Latter-day Saints in NY, called
• In 5 years they attracted
some 8,000 followers
• They faced hostility for their
beliefs, like men being able to
have several wives
• They migrated to area around
Great Salt Lake (present-day
Utah) with Brigham Young
The Gold Rush
Gold Fever
Rush to California
• Gold is discovered in the
American River in 1848  many
headed to CA to strike it rich!
• Most in the US did not believe
until President James K. Polk
announced he believed the
supply to be large and found in
various places
• The gold rush is the mass
migration of miners and
businesspeople to CA
• The migrants that left for CA in
1849 were called forty-niners
• More than 80,000 arrive
• 80% are from the US
• Most traveled over land; others
booked passage on a ship
Booming Cities
• Upon reaching CA, most
miners moved into mining
camps in the gold fields
• Others, especially
businessmen, settled in the
• San Francisco in 1848 had 800
people, one year later more than
• by 1860 it was home to some
60,000 people
Major Effects of Westward Migration
The Oregon Treaty
Communication Links
• James K. Polk, presidential
candidate, campaigned to
secure the region of OR for the
• “Fifty-four Forty or Fight!” was
talking about the 54º40’ N
latitude which marked the
northern boundary of Oregon
• Polk won presidency but
retreated from his pledge and
settled at the 49th parallel with
Great Britain
• Westward migration led to a need
for better communication
• Butterfield Trail, private
stagecoach line ran
• Pony Express, relied on young
riders and fast horses
• Telegraph linked East to West and
made the Pony Express obsolete
• The greatest effect was on the
Native Americans whose life was
changed forever.
Main Idea: American settlers in Texas
revolted against the Mexican
government and created the
independent Republic of Texas.
The Spanish Settle Texas
• Hundreds of Native American
groups had lived in TX for thousands
of years
• Spanish were the first Europeans to
visit Texas
• They attempt to settle Texas with
the mission system-small settlement
started with goal to convert Native
Americans to Catholicism
• Usually included a fort
• They believed it would make the
Native Americans loyal to the
Spanish – they did not.
Americans Move into Texas
• Moses Austin (1820), former banker,
proposed a plan to the Spanish to settle
• Austin died before he could start the colony
• Stephen Austin (his son) carried out his
• 1823, he established his colony
• Mexico had gained its independence from
• It granted large pieces of land to
empresarios-contractors who agreed to
start colonies
• By 1830 more than 30,000 settlers in TX
• 4,000 were Tejanos-Texans of Mexican heritage
The Texas Revolution
Conditions of Settling Texas
Tensions in Texas
• Become Mexican citizen
• Adopt the Roman Catholic
• Outlawed slavery
• Most settlers did not comply
• Believed they were Americans
who happened to live in Mexico
and remained loyal to the US
• Mexicans grew concerned
• 1827, US offers to buy Texas
and Mexico refuses
• Texans began to protest, which
grew bloody
• Antonio Lopez de Santa Anna
became president of Mexico
• Texans attack Mexican force at
Gonzales and won
• Start of Texas Revolution
• Cancelled empresario contracts
• Put tariffs on trade with US
• Angered settlers
• Texans formed a government
• Sam Houston given task of raising
The Alamo
• Texan forces captured San
Antonio, which contained a fort
called the Alamo
• Santa Anna led an army of
6,000 to the fort
• William Travis, Texan leader,
only had 200
• Nearly all were killed when the
Mexican army attacked
• Texans were also defeated at
Refugio and Goliad (Mexican
army massacred prisoners)
• Santa Anna followed Houston’s
forces to San Jacinto
• Texans defeated the Mexicans and
captured Santa Anna
• Santa Anna was forced to sign the
Treaties of Velasco
• Texas became a separate nation
called the Republic of Texas
Main Idea: Soon after annexing
Texas, the United States declared
war on Mexico
The Annexation of Texas
• Americans believed in manifest
destiny-adds large land area to
• Texas Revolution just like
American Revolution
• Texas allowed slavery, meaning
more political power
• Fear of bearing substantial
Texas debt
• Opposed spread of slavery
increasing voting power in
• Nothing in Constitution about
admitting an independent
Annexation approved
Texas apart of US
December 29, 1845
Tensions between the US and Mexico
Texas Annexation
• 1836, Texas gained independence from Mexico
• Enraged Mexican government, still believed it had been
unfairly taken
• TX boundary is still disputed by the Mexican government
• US 1st recognized Nueces River as boundary
• Texans claimed it was further south at the Rio Grande
• President Polk wanted the land between Texas and the Pacific
• Polk sent a special messenger to Mexico (1845) and offered to pay $30
million for New Mexico and California
• No one would meet with the messenger
Mexican-American War
• Meanwhile, Polk ordered General Zachary Taylor to advance into
the disputed territory between the Nueces and Rio Grande
• April 25, some of his soldiers fought a skirmish in the region
• Polk used this event as an excuse to request Congress to declare
war on Mexico
• Ignoring boundary was in dispute, Polk charged the Mexicans had
“invaded our territory and shed the blood of our fellow-citizens on
our own soil.”
• US declared war on Mexico May 13, 1846
Fighting the War
• US uses aggressive strategy to win
• General Stephen Kearny easily
captured towns hoping to gain
control of California
• Rebels forced Mexican gov’t to
sign treaty turning over CA on
June 14, 1846 ~ became Republic
of California
• General Winfield Scott landed at
the Gulf and led forces inland to
Mexico City in Sept. 1847
• Within months, US forces had
captured NM and CA, Mexico’s
capital fell  gov’t
Results of the War
• Treaty of Guadalupe Hidalgo
• Signed in 1848
• Mexico forced to turn over to the US a
huge tract of land (Mexican Cession)
• US paid Mexico $15 million and drop
the $3 million damages
• Gadsden Purchase
• 1853
• Clarified the treaty boundary and
transferred more land to the US
• Polk pleased, not all Americans
proud of war
• Debate continues today over

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