The United States acquired its first overseas territory, Guam, in 1898 as a result of the Spanish-American War.

Vermont was the first state to join the United States after the American Revolution, in 1791.

Manifest Destiny was the policy that the United States pursued in the late 19th and early 20th centuries to expand its influence and control over other countries.

The Spanish-American War was a war between the United States and Spain in 1898.

The United States acquired Cuba, Puerto Rico, the Philippines, and Guam as a result of the Spanish-American War.

The Monroe Doctrine was the policy that the United States pursued in the early 20th century to prevent other countries from interfering in its affairs in the Western Hemisphere.

The Open Door Policy was the policy that the United States pursued in the early 20th century to promote its economic interests in China.

Big Stick Diplomacy was the policy that the United States pursued in the early 20th century to use military force to protect its interests in the Caribbean and Central America.

Moral Diplomacy was the policy that the United States pursued in the early 20th century to promote democracy and human rights in other countries.

The Philippine-American War was a war between the United States and the Philippines from 1899 to 1902.

The Mexican-American War was a war between the United States and Mexico from 1846 to 1848.

The Cuban-American War was a war between the United States and Cuba from 1898 to 1902.

The Puerto Rican-American War was a war between the United States and Puerto Rico from 1898 to 1902.

The Roosevelt Corollary was the policy that the United States pursued in the early 20th century to prevent other countries from acquiring territory in the Western Hemisphere.

Dollar Diplomacy was the policy that the United States pursued in the early 20th century to promote its economic interests in Latin America.