Chapter 9 Section 3
Effects of Westward Expansion
Objectives
•
Explain the effects of the Mexican-American War
on the United States.
•
Trace the causes and effects of the California
Gold Rush.
•
Describe the political impact of California’s
application for statehood.
Treaty of Guadalupe Hidalgo.
• Mexico had to sell a third
of its territory to the
United States (1.2 million
square miles).
• For $15 million, the
United States obtained
California and New
Mexico. The Texas border
was set at the Rio
Grande.
• Mexico was humiliated
and remained bitter
toward the United States
for decades.
Gadsden Purchase
• Territory in southern
Arizona and New Mexico
was purchased from
Mexico for a potential
route for a
transcontinental railroad.
• The lands obtained from
Mexico increased the
area of the United States
by a third.
• The land formed New
Mexico, California,
Nevada, Utah, Arizona,
and half of Colorado.
Expansion of Slavery
• In 1846, the Wilmot Proviso
proposed a ban on slavery in
the territories obtained from
Mexico.
• The Proviso passed in the
House, but failed in the
Senate. Both Whigs and
Democrats voted along
sectional lines.
• The Proviso brought the issue
of slavery before Congress,
which had tried avoid the topic
for decades.
Gold Rush
• Gold was found
at Sutter’s Mill near
Sacramento, California.
• The resulting California Gold
Rush brought a mass
migration of 80,000 fortune
hunters west.
• They were called forty-niners.
Half traveled overland; the rest
either sailed around South
America or to Panama, where
they crossed the isthmus and
caught ships up the coast.
The Gold Rush attracted miners from South
America and China. California’s population grew
from 14,000 in 1847 to 225,000 in 1852.
The first miners used metal pans, shovels and picks
to find gold along river banks. Few became wealthy
using this method, called placer mining.
Merchants and traders made more money selling
goods to the miners than the miners earned
themselves.
Mining Camps
• Life in the mining
camps was crude and
rough. Many died of
disease, especially
cholera and
dysentery.
• Fights and violence
were common. Only a
few of the miners
were women.
Mining Process
• Initially, miners panned
for gold.
• Mining soon became
mechanized to make it
more efficient. One
method was to divert a
river or stream to expose
the river bed.
• Hydraulic mining
employed jets of water to
erode gravel hills into
long lines of sluices which
caught the gold.
• Hydraulic mining left
heavy sediments in
the river and caused
a great deal of
environmental
damage.
Gold mining soon
became too
expensive for
individual miners.
The democratic era in the gold fields did
not last long. Individual prospectors
were soon replaced by wealthy investors
paying wages.
Minorities in the Gold Rush
• Minorities faced violence in the
gold fields and discrimination
in the courts.
• Native Americans were killed
or lost their land. Others found
work on farms and ranches.
• Old Mexican land titles were
generally ignored. Most of the
original Californians were
dispossessed.
• The Chinese were targeted by
a foreign miner’s tax and mob
violence.
• Mexicans also had to pay a
foreign miner’s tax.
San Francisco
• San Francisco
became the gateway
to the California
gold fields.
• After 1848, the city
grew rapidly from a
tiny Spanish
settlement into a
major American city.
Growth of San Francisco
Year
Population
1848
800
1849
25,000
1852
36,000
1860
57,000
Arguments over California
• By October 1849, California
prepared to seek admission
into the Union.
• Most Californians opposed
slavery, so California’s
admission as a free state
would tip the 15 slave and 15
free state balance
in the U.S. Senate.
• Debate over the spread of
slavery into the territories
obtained from Mexico became
a leading cause of the Civil
War.