2 Dec 1823: Monroe Doctrine President James Monroe announced a U.S. foreign policy opposing European colonialism in the Americas.
2
1825
26 Oct 1825: Erie Canal completed The Erie Canal officially opened, revolutionizing transportation and trade.
3
1826
4 Jul 1826: Jefferson and Adams die Former presidents Thomas Jefferson and John Adams both died on the 50th anniversary of the Declaration of Independence.
4
1829
4 Mar 1829: Andrew Jackson inaugurated Andrew Jackson was sworn in as the seventh President, beginning the "Age of Jackson."
5
1830
28 May 1830: Indian Removal Act President Andrew Jackson signed a law forcing the relocation of Native American tribes from their ancestral lands.
6
1836
2 Mar 1836: Texas declares independence Texas declared its independence from Mexico, leading to the Texas Revolution.
6 Mar 1836: Battle of the Alamo Texan defenders of the Alamo were defeated by Mexican forces after a 13-day siege.
28 Dec 1836: Battle of San Jacinto Texan forces led by Sam Houston defeated the Mexican army, securing Texas independence.
7
1838
28 May 1838: Trail of Tears begins The forced relocation of the Cherokee Nation from their homeland began, resulting in thousands of deaths.
8
1845
29 Dec 1845: Texas annexed by U.S. The Republic of Texas was annexed by the United States, becoming the 28th state.
9
1846
13 May 1846: Mexican-American War begins The United States declared war on Mexico over a border dispute in Texas.
10
1848
24 Jan 1848: California Gold Rush begins Gold was discovered at Sutter's Mill, California, triggering a massive migration of "forty-niners."
24 Jan 1848: Gold discovered in California James W. Marshall discovered gold at Sutter's Mill in Coloma, California, beginning the California Gold Rush.
2 Feb 1848: Treaty of Guadalupe Hidalgo The treaty was signed, ending the Mexican-American War and ceding significant territory to the United States.
11
1850
9 Sep 1850: Compromise of 1850 A series of five bills passed to address the issue of slavery, including admitting California as a free state and enacting the Fugitive Slave Act.