Ř The United States expanded its territory westward to
stretch from the Atlantic to the Pacific coast.
Ř Today, one-third of all Americans
live in the areas added to the United States in 1848.
ONE AMERICAN'S STORY
Henry Clay sneered, "Who is James K. Polk?" Clay
had just
learned the name of the man nominated by Democrats to run against him
for president in 1844. "A mistake!" answered Washington insiders. News of Polk's nomination
was flashed to the capital by the newly invented telegraph machine. People were
convinced that the machine didn't work. How could the Democrats choose Polk? A
joke! Polk was America's first "dark horse," a
candidate who received unexpected support.
The Democrats had nominated this little-known man only when
they could not agree on anyone else. Still, Polk wasn't a complete nobody. He had been governor of Tennessee and served seven terms in Congress.
Polk was committed to national expansion. He vowed to annex Texas and take over Oregon. Americans listened and voted. When
those votes were counted, Clay had his answer. James Knox Polk was the eleventh
president of the United States. During his campaign, Polk's ideas
about expanding the country captured the attention of Americans. After his
election Polk looked for ways to expand the nation.
Americans Support Manifest Destiny

The abundance of land in the West seemed to hold great
promise for Americans. Although populated with Native Americans and Mexicans,
those lands were viewed by white settlers as unoccupied. Many Americans wanted
to settle those lands themselves, and they worried about competition from other
nations. Mexico occupied the southwest lands, and Britain shared the northwest Oregon Territory with the United States.
Many Americans believed that the United States was destined to stretch across the
continent from the Atlantic Ocean to the Pacific Ocean. In 1845, a newspaper editor named John O'Sullivan
gave a name to that belief.
A VOICE FROM THE PAST
Our manifest destiny [is] to
overspread and possess the whole of the continent which Providence [God] has given us for the
development of the great experiment of liberty and . . . self-government.
John O'Sullivan, United States Magazine and Democratic Review
John O'Sullivan used the word manifest to mean clear or
obvious. The word destiny means events sure to happen. Therefore, manifest
destiny suggested that expansion was not only good but bound to happen, even if
it meant pushing Mexicans and Native Americans out of the way. After Polk's
election in 1844, manifest destiny became government policy. The term
"manifest destiny" was new, but the idea was not.

By the 1840s, thousands of Americans had moved into the Oregon Territory. Since 1818, Oregon had been occupied jointly by the United States and Britain. In his campaign, Polk had talked
of taking over all of Oregon. "Fifty-four forty or
fight!" screamed one of his slogans. The parallel of 54° 40' N latitude
was the northern boundary of the shared Oregon Territory. Rather than fight for all of Oregon, however, Polk settled for half. In
1846, the United States and Great Britain agreed to divide Oregon at the 49th parallel. This
agreement extended the boundary line already drawn between Canada and the United States. Today this line still serves as
the border between much of the United States and Canada.
Troubles with Mexico
Polk had good reason for avoiding war with Britain over Oregon. By 1846, he had much bigger
troubles brewing with Mexico over Texas.
In 1845, Congress admitted Texas as a slave state, in spite of
Northern objections to the spread of slavery. However, Mexico still claimed Texas as its own. Mexico angrily viewed this annexation as
an act of war. To make matters worse, Texas and Mexico could not agree on the official
border between them. Texas claimed the Rio Grande, a river south of San Antonio, as its southern boundary. Mexico insisted on the Nueces River as the border of Texas. The difference in the distance
between the two rivers was more than 100 miles at some points. Many thousands
of miles of territory were at stake.
Mexico said it would fight to defend its
claim. Hoping to settle the dispute peacefully, Polk sent John Slidell, a Spanish-speaking
ambassador, to offer Mexico $25 million for Texas, California, and New Mexico. But Slidell's diplomacy failed.
Believing that the American people supported his expansion
plans, Polk wanted to force the issue with Mexico. He purposely ordered General
Zachary Taylor to station troops on the northern bank of the Rio Grande. This river bank was part of the
disputed territory. Viewing this as an act of war, Mexico moved an army into place on the
southern bank. On April 25, 1846, a Mexican cavalry unit crossed the
Rio
Grande. They ambushed an American patrol and killed or wounded 16 American
soldiers.
When news of the
attack reached Washington, Polk sent a rousing war message to
Congress, saying, "Mexico has invaded our territory and shed American
blood upon American soil." Two days later, Congress declared war. The War
with Mexico had begun. Thousands of volunteers,
mostly from western states, rushed to enlist in the army. Santa Anna, who was
president of Mexico, built up the Mexican army.
However, Americans had mixed reactions to Polk's call for
war. Illinois representative Abraham Lincoln questioned the truthfulness
of the president's message and the need to declare war. Northeasterners
questioned the justice of men dying in such a war. Slavery became an issue in
the debates over the war. Southerners saw expansion into Texas as an opportunity to extend slavery
and to increase their power in Congress. To prevent this from happening,
antislavery representatives introduced a bill to prohibit slavery in any lands
taken from Mexico. Frederick Douglass, the
abolitionist, summarized the arguments.
A VOICE FROM THE PAST
“The determination of our
slaveholding President to prosecute the war, and the probability of his success
in wringing from the people men and money to carry it on, is made evident, . . . None seem willing to take their stand for
peace at all risks; and all seem willing that the war should be carried on in
some form or other.”
Frederick Douglass in The North Star, January 21, 1848
Despite opposition, the United States plunged into war. In May 1846,
General Taylor led troops into Mexico. Many Americans thought it would be
easy to defeat the Mexicans, and the war would end quickly.

Capturing New Mexico and California
Not long after the war began, General Stephen Kearny a U.S.
Army officer-and his men left Fort Leavenworth, Kansas, with orders to occupy New Mexico. Then they were to continue west to
California. As his troops marched along the Santa Fe Trail, they sang songs like this one.
A VOICE FROM THE PAST
Old Colonel Kearny, you can bet,
Will keep the boys in motion,
Till Yankee Land includes the sand
On the Pacific Ocean
Six weeks and 650 hot and rugged miles later, Kearny's army entered New Mexico. Kearny took New Mexico without firing a shot. Then Kearny and a small force of soldiers
marched on toward California, which had only 6,000 Mexican
residents. The remainder of the force moved south toward Mexico.
In California, Americans led by the explorer John
C. Frémont rebelled against Mexican rule in the Bear
Flag Revolt. They arrested the Mexican commander of Northern California and raised a crude flag showing a
grizzly bear sketched in blackberry juice. The rebels declared California independent of Mexico and named it the Republic of California. In the fall, U.S. troops reached California and joined forces with the rebels.
Within weeks, Americans controlled all of California.
The Invasion of Mexico
The defeat of Mexico proved far more difficult. The
Mexican army was much larger, but the U.S. troops were led by well-trained
officers. American forces invaded Mexico from two directions. General Taylor
battled his way south from Texas toward the city of Monterrey in northern Mexico. On February
22, 1847,
his 4,800 troops met General Santa Anna's 15,000 Mexican soldiers near a ranch
called Buena
Vista.
After the first day of fighting, Santa Anna sent Taylor a note offering him a chance to
surrender. Taylor declined. At the end of the second
bloody day of fighting, Santa Anna reported that "both armies have been
cut to pieces." However, it was Santa Anna who retreated after the Battle
of Buena Vista. The war in the north of Mexico was over.
In Southern Mexico, fighting continued. A second force led by General
Winfield Scott landed at Veracruz on the Gulf of Mexico and battled inland toward Mexico City. Outside the capital, Scott met
fierce resistance at the castle of Chapultepec (chuhoPOOLotuhopek).
About 1,000 soldiers and 100 young military cadets bravely defended the
fortress. Despite their determined resistance, Mexico City fell to Scott in September 1847. As
he watched, a Mexican officer sighed and said, "God is a Yankee."
The Mexican Cession
On February 2, 1848, the war officially ended with the
Treaty of Guadalupe Hidalgo. In this treaty, Mexico recognized that Texas was part of the United States, and the Rio Grande was the border between the nations.
Mexico also ceded, or gave up, a vast region known as the
Mexican Cession. This area included the present-day states of California, Nevada, Utah, most of Arizona, and parts of New Mexico, Colorado, and Wyoming. Together with Texas, this land amounted to almost
one-half of Mexico. The loss was a bitter defeat for Mexico, particularly because many Mexicans
felt that the United States had provoked the war in the hope of
gaining Mexican territory.
In return, the United States agreed to pay Mexico $15 million. The United States would also pay the $3.25 million of
claims U.S. citizens had against Mexico. Finally, it also promised to
protect the 80,000 Mexicans living in Texas and the Mexican Cession.
Mexicans living in the United States saw the conquest of their land
differently. Suddenly they were a minority in a nation with a strange language,
culture, and legal system. At the same time, they would make important
contributions to their new country. They taught new settlers how to develop the
land for farming, ranching, and mining. A rich new culture resulted from the
blend of many cultures in the Mexican Cession.
"From Sea to Shining Sea"
The last bit of territory added to the continental United States was a strip of land across what is
now southern New Mexico and Arizona. The government wanted the land as
a location for a southern transcontinental railroad. In 1853, Mexico sold the land-called the Gadsden Purchase- to the United States for $10 million.

On July
4, 1848, in
Washington, President Polk laid the
cornerstone of a monument to honor George Washington. In Washington's day, the western border of the United States was the Mississippi River. The United States in 1848 now stretched "from
sea to shining sea." In August, Polk learned that gold had been found in California.
- United States had a divinely inspired
mission to expand and to spread democracy throughout North America. _________________________
- In 1845, Congress admitted
_________________________as a slave state.
- What President sent troops into a region claimed
by both the United States and
Mexico_________________________
- Polk ordered Zachary
Taylor to station troops on the northern bank of the _________________________River, disputed territory with Mexico.
- Over a border dispute, in May 1846,The United States went to war the
_________________________.
- In California, Americans led by the explorer
John C. Frémont rebelled against Mexican rule in
the __________________
- Despite their determined resistance,
__________fell to the Americans in September 1847.
- On February 2, 1848, the war with Mexico officially ended with the
Treaty of _________________________.
- Mexico was forced to give up, a vast
region of land known as the Mexican _________________________.
- The last bit of territory the United States bought from Mexico was a strip of land called the
_________________________Purchase.