Manifest Destiny and Westward Expansion

Definition: The term "Manifest Destiny" refers to the 19th-century doctrine that it was the divine right of the United States to expand its territory across the North American continent, from the Atlantic Ocean to the Pacific Ocean.
Origin of the Term: The exact origins are unclear, but it is commonly attributed to the American journalist John L. O’Sullivan.
Cultural Representation: John Gast's painting "American Progress" (1872) embodies the spirit of Manifest Destiny.

Early American Expansionism (Pre-1840): Before 1840, many leaders envisioned the rise of independent nations within North America, all upholding U.S. republican values.

Presidential Election of 1840:
- The election was largely devoid of major issues, resulting in Whig candidate William Henry Harrison defeating incumbent Martin van Buren.
William Henry Harrison's Presidency:
- Known as "Old Tippecanoe," he delivered his inaugural address in March 1841 but died after only one month in office, marking the shortest presidency in U.S. history.
Succession by John Tyler:
- John Tyler, Harrison's successor, faced challenges during his presidency, famously vetoing a national bank re-establishment and facing expulsion from the Whig party due to his political conflicts.

Major Sources of Friction:
- Copyright Issues: The U.S. lacked rigorous copyright laws, causing tensions.
- Financial Defaults: Several state governments in the U.S. defaulted on loans from British institutions.
- Territorial Disputes: There were border disputes in Maine and the Oregon territory.
- Canadian Rebellions: U.S. citizens provided support to Canadian rebels, heightening tensions.

Background:
- The Aroostook War was a conflict over the Maine-New Brunswick border.
- The Webster-Ashburton Treaty (1842) settled these disputes, favoring British land claims and establishing a boundary at the 49th Parallel.

Map highlighting new territories acquired by the U.S.:
- Texas: Annexed in 1845, stemming from its earlier fight for independence.
- Oregon Territory: Dispute with Britain resolved in 1846.
- Mexican Cession: Acquired following the conclusion of the Mexican-American War in 1848.

Texas Independence:
- Following struggles for independence from Mexico in 1836, the Republic of Texas sought union with the U.S.
James K. Polk's Role:
- Polk ran on a platform of Texas annexation; after his electoral victory, Texas was approved for admission under Tyler.
- Texas formally entered the U.S. on December 29, 1845, provoking protests from Mexico, which viewed it as a territory theft.

Competing Claims:
- The slogan "54-40 or Fight!" represented American claims to the entirety of the Oregon Territory.
Resolution and Compromise:
- The border was settled at the 49th parallel in 1846 under negotiations between the U.S. and Britain, influenced by the ongoing conflict with Mexico.

Causes:
- Following the failure to purchase California from Mexico, Polk incited the war to claim the territory.
Controversial Declaration of War:
- The decision was criticized as "Mr. Polk's War," with notable figures like Abraham Lincoln questioning its legitimacy and constitutional basis.
Military Leaders:
- Key commanders included General Zachary Taylor and General Winfield Scott, alongside future leaders such as Ulysses S. Grant and Robert E. Lee.

Invasion Routes:
- There were multiple military campaigns, including land invasions from the north and naval assaults via the Gulf of Mexico.
Battle of Chapultepec:
- This significant battle, along with the capture of Mexico City, led to the Mexican acceptance of peace.

Terms of Agreement (1848):
- The U.S. acquired Mexican northern provinces.
- A payment of $15 million was made to Mexico for the territory.
- The U.S. also assumed $3 million in claims by American citizens against Mexico, finalizing borders that laid the groundwork for modern U.S. boundaries.