Which doctrine, articulated in the early 19th century, justified American expansion across the continent by asserting that it was the nation's destiny?

Which acquisition was crucial in providing the United States with key ports and control of the Mississippi River, facilitating trade and economic expansion?

Which legislation in the mid-19th century attempted to resolve conflicts between free and slave states by admitting Missouri as a slave state and Maine as a free state?

What was the major outcome of the California Gold Rush that impacted the economic expansion of the United States in the mid-19th century?

Which significant event marked the beginning of territorial conflicts between the United States and neighboring countries during the period from 1803 to 1865?

What major consequence did the westward expansion of the United States have on Native American populations during the 19th century?

Which significant turning point in the period from 1803 to 1865 led to increased tensions over slavery in new territories?

How did the invention of the cotton gin in 1793 impact economic and geographic expansion in the United States?