Maine
Canada
Territorial
Expansion by Mid-19th Century
•In 1839, fighting broke
out between Maine &
Canada over the
disputed Maine border
•Webster-Ashburton
Treaty (1842) settled
the issue:
•The U.S. received ½
the disputed land
•Established a clear
border in Maine
War With Mexico
Tyler and Texas
 In
1844, President Tyler called for
the annexation of Texas:
–Tyler & Calhoun created a
propaganda campaign that
England wanted Texas & would
Tyler
needed
to
make
Texas
a
campaign
end
to
slavery
there
issue in the election of 1844 because he
–Northern
Senators
notParty
fall &
had
been kicked
out of thedid
Whig
for it &to refused
theman
hoped
appeal to to
theratify
common
treaty to annex Texas
–Tyler was not nominated by
either party in the 1844 election
 In
Polk
&
Texas
Annexation
“Dark Horse” candidate
1844, the Whigs nominated
Henry Appealed
Clay & the
Democrats
to the
South
nominated James Polk
 Polk won on expansionist platform
– Called for Texas annexation
– Called for an end to the joint
U.S.-British control of Oregon
 Polk & Congress interpreted the
Appealed
to
the
North
election as mandate for expansion
& Texas was quickly made a state
Oregon
th Century
Oregon
Territorial Expansion by Mid-19
• U.S. & Britain
jointly occupied
Oregon (Spain
relinquished its
claims to Oregon
in the Adams-Onis
Treaty of 1819)
• Britain claimed a
greater stake of
Oregon via Hudson
Bay Co. (fur trade)
Oregon
residents
wanted
the
entire
Polk
and
the
Oregon
Question
territory—“54º40’ or fight!”
 In
1846, President Polk notified
Britain that the U.S. wanted full
control of Oregon
 England proposed & the Senate
approved the division of Oregon
along 49o parallel in 1846
 Benefits: the U.S. gained its 1st
deep-water port in the Pacific &
Northern abolitionists saw Oregon
as a balance to slave-state Texas
Northwest
Boundary
Dispute
England &
54’
40º
the U.S.
to
oragreed
Fight!
divide
Oregon at
the 49o
parallel
Mexican-American War
 Mexico
recognized Texas’
independence & U.S. annexation,
but disagreed over Texas’
northern border
 In
May 1846, Polk sent U.S.
General Zachary Taylor beyond
the Rio Grande River which led to
the Mexican-American War
John C Fremont won
The Mexican-American
War
in California
Zachary Taylor won in
northern Mexico
Stephen Kearney
captured New Mexico
Winfield Scott
captured Mexico City
Settling the Mexican-American War
 In
1848, U.S. & Mexico agreed to
the Treaty of Guadalupe Hidalgo:
–Rio Grande became the U.S.
southern border
–The U.S. grew 20% by adding
the Mexican Cession—presentday NM, AZ, CA, Utah, NV, &
parts of CO & WY
–Added territory in NM & AZ with
the Gadsden Purchase in 1853
The Mexican Cession
Not everyone supported the
Mexican-American War
Whigs opposed it
Northerners saw it
as a Southern
“slave-power” plot
to extend slavery
Wilmot Proviso


The 1846 Wilmot Proviso was a bold attempt by
opponents of slavery to prevent its introduction
in the territories purchased from Mexico
following the Mexican War. Named after its
sponsor, Democratic representative DAVID
WILMOT of Pennsylvania, the proviso never
passed both houses of Congress, but it did ignite
an intense national debate over slavery that led
to the creation of the antislavery REPUBLICAN
PARTY in 1854.
California
Territorial Expansion by Mid-19th Century
California
•In 1833, the new
Mexican gov’t
awarded land grants
to rancheros who
quickly replaced the
missionary padres
•In 1830s, the U.S.
was eager to enter
the cowhide trade
The Bear Flag Republic
Like Texas,settlers
California operated as an
 California
independent nation; the California
used
John
Republic
existed for one month from
Fremont’s
June 1846 to July 1846 when it was
annexed of
by the United States
occupation
California
became a U.S. state as
California
during
part
of
the
Compromise
of
1850
the Mexican-
American War as
an opportunity to
revolt from
Mexico in 1846
The California Gold Rush
 The
discovery of gold in 1848 led
to a massive influx of prospectors
in 1849 (the “forty-niners”) :
–Few miners struck it rich; Real
money was in supplying miners
with food, booze, & provisions
–Led to a population boom,
agriculture, & multicultural
society in California
Where the 49ers Came From
80%
United
States
Europe &
Asia
13%
7%
Latin
America
 San
Francisco
before the gold
rush
 San
Francisco
after the gold
rush
Conclusions:
The Costs of Expansion
U.S. Territorial Expansion
The Costs of Expansion
 The impact
of territorial expansion:
–Historian Fredrick Jackson
Turner noted in the 1890s that
expansion shaped Americans
into an adventurous, optimistic,
& democratic people
–But, expansion created sectional
conflicts between the North &
South, especially over slavery