U.S. vice president Theodore Roosevelt first publicly used the phrase "speak softly and carry a big stick" (cartoon pictured) at the Minnesota State Fair, describing his philosophy of negotiating peacefully while simultaneously threatening to use military force.

Under the mediation of U.S. president Theodore Roosevelt, the Russo-Japanese War officially ended with the signing of a treaty at the Portsmouth Naval Shipyard in Maine.

Theodore Roosevelt became President of the United States at age 42, the youngest person ever to do so, eight days after William McKinley was fatally wounded in Buffalo, New York.

Approximately 400 workers completed the 60-foot (18 m) busts of U.S. presidents George Washington, Thomas Jefferson, Theodore Roosevelt, and Abraham Lincoln at Mount Rushmore in South Dakota.

President Theodore Roosevelt announced the Roosevelt Corollary to the Monroe Doctrine, justifying the exercise of "international police power" by the U.S. in the Western Hemisphere.