The expansion of US power, from the 1840s to the 1930s

Manifest Destiny and the Expansion Westward (1840-1869)

Notion of Manifest Destiny was the belief that Americans were chosen to expand across North America due to divine sanction.
Expansion kicked off with Texas’ admission into the Union in 1845, followed by the Oregon Treaty in 1846 with Britain that secured Oregon and Washington.
The Mexican-American War (1846-1848) concluded with the Treaty of Guadalupe Hidalgo which saw Mexico cede California and much of the Southwest to the US.
Gold Rush of 1848 brought migrants west, and California became a state in 1850.
The Transcontinental Railroad, completed in 1869 marked a significant step in connecting the East Coast with the newly-settled West.

Rise of Imperial Power (1890-1930)

Spanish-American War (1898) saw the US acquire Puerto Rico, Guam, and the Philippines, underlining America’s emergence as a global power.
Annexation of Hawaii in 1898 also marked America’s expansion into the Pacific.
Open Door Policy towards China in 1899-1900 emphasized America’s commercial and diplomatic influence in the Far East.
Panama Canal, opened in 1914, was a monumental infrastructural achievement, signalling US control over crucial global trade routes.
After its victory in World War I, America emerged as one of the world’s leading powers, also reflected in the League of Nations negotiations.

Depression, New Deal, and Global Reach (1930-1939)

The Great Depression, following the Wall Street Crash of 1929, initially undermined America’s global standing, possibly due to economic isolationism.
Roosevelt’s New Deal aimed at reforming the economy, providing relief to unemployed, and restoring confidence. Its success was debated but it still marked a significant increase in federal power and influence.
Good Neighbor Policy established in the 1930s improved US relations with Latin America, reducing direct intervention while maintaining economic influence.
US rose to be a global economic leader, with the 1934 Reciprocal Trade Agreements Act paving the way for freer international trade.

Final note: Post 1941 America’s power expands further due to its involvement in World War II but it is not covered under this topic and will be discussed separately.

Remember, keep making connections between these points to construct a comprehensive narrative of the expansion of US power between 1840-1939.