In the United States, a five month strike by United Mine Workers ends.

El Yunque National Forest in Puerto Rico becomes part of the United States National Forest System as the Luquillo Forest Reserve.

Cuba leases Guantánamo Bay to the United States "in perpetuity".

The Hay-Herran Treaty, granting the United States the right to build the Panama Canal, is ratified by the United States Senate. The Colombian Senate would later reject the treaty.

With the encouragement of the United States, Panama separates from Colombia.

The Hay-Bunau-Varilla Treaty is signed by the United States and Panama, giving the United States exclusive rights over the Panama Canal Zone.

Construction begins by the United States on the Panama Canal.

Polytechnic University of the Philippines founded as Manila Business School through the superintendence of the American C.A. O'Reilley.

The first underground New York City Subway line opens; the system becomes the biggest in United States, and one of the biggest in world.

San Francisco public school board sparks United States diplomatic crisis with Japan by ordering Japanese students to be taught in racially segregated schools.

The cornerstone is laid at Washington National Cathedral in the U.S. capital.

United States troops leave Cuba with the exception of Guantanamo Bay Naval Base after being there since the Spanish-American War.

African-American boxer Jack Johnson knocks out white boxer Jim Jeffries in a heavyweight boxing match sparking race riots across the United States.

The first US patent for inventing the traffic lights system is issued to Ernest E. Sirrine.

Victor Berger (Wisconsin) becomes the first socialist congressman in U.S..

The Girl Guides (later renamed the Girl Scouts of the USA) are founded in the United States.

Massachusetts becomes the first state of the United States to set a minimum wage.

United States Marines invade Nicaragua to support the U.S.-backed government installed there after José Santos Zelaya had resigned three years earlier.

United States Marines invade Nicaragua to support the U.S.-backed government installed there after José Santos Zelaya had resigned three years earlier.

Alaska becomes a United States territory.

Dedication of the Lincoln Highway, the first automobile road across United States.

The United States introduces an income tax.

World War I: Germany invades Belgium. In response, the United Kingdom declares war on Germany. The United States declare their neutrality.

A male servant of American architect Frank Lloyd Wright sets fire to the living quarters of the architect's Wisconsin home, Taliesin, murders seven people and burns the living quarters to the ground.

The United States Federal Trade Commission (FTC) is established by the Federal Trade Commission Act.

The Federal Reserve Bank of the United States officially opens.

Jewish American Leo Frank is lynched for the alleged murder of a 13-year-old girl in Marietta, Georgia.

Eight American planes take off in pursuit of Pancho Villa, the first United States air-combat mission in history.

The United States passes the Philippine Autonomy Act.

Jeannette Rankin is the first woman elected to the United States Congress.

World War I: The United States breaks off diplomatic relations with Germany a day after the latter announced a new policy of unrestricted submarine warfare.

World War I: The U.S. ambassador to the United Kingdom is given the Zimmermann Telegram, in which Germany pledges to ensure the return of New Mexico, Texas, and Arizona to Mexico if Mexico declares war on the United States.

World War I: The U.S. ambassador to the United Kingdom is given the Zimmermann Telegram, in which Germany pledges to ensure the return of New Mexico, Texas, and Arizona to Mexico if Mexico declares war on the United States.

World War I: Conscription begins in the United States as "Army registration day".

World War I: The United States declares war on Austria-Hungary.

Great train wreck of 1918: in Nashville, Tennessee, an inbound local train collides with an outbound express killing 101 and injuring 171 people, making it the deadliest rail accident in United States history.

World War I: In the Argonne Forest in France, United States Corporal Alvin C. York leads an attack that kills 25 German soldiers and captures 132.

U.S. President Woodrow Wilson sails for the World War I peace talks in Versailles, becoming the first US president to travel to Europe while in office.

Temperance movement: The United States ratifies the Eighteenth Amendment to the United States Constitution, authorizing Prohibition in the United States one year after ratification.

Oregon places a 1 cent per U.S. gallon tax on gasoline, becoming the first U.S. state to levy a gasoline tax.