1905 in the United States

Federal government

• President: Theodore Roosevelt (R-New York)
• Vice President:

vacant (until March 4)

Charles W. Fairbanks (R-Indiana) (starting March 4)

• Chief Justice: Melville Fuller (Illinois)
• Speaker of the House of Representatives: Joseph Gurney Cannon (R-Illinois)
• Congress: 58th (until March 4), 59th (starting March 4)

January–June

• January 6 – The Senate confirms the nomination of William D. Crum, an African-American, to the office of collector of customs at Charleston, South Carolina after Crum's nomination by President Theodore Roosevelt.^[1]
• January 30 – The Supreme Court renders its unanimous decision in the landmark case of Swift & Co. v. United States, allowing the federal government to regulate monopolies.^[2]
• March 4 – President Theodore Roosevelt begins his first full term. Charles W. Fairbanks is sworn in as Vice President of the United States.
• March 10 – In Cleveland, Ohio, Cassie Chadwick is sentenced for 14 years in prison for fraud.
• March 17 – Franklin D. Roosevelt marries his fifth cousin Eleanor Roosevelt; President Roosevelt, the bride's uncle, gives her away.
• March 20 – Grover Shoe Factory disaster: A boiler explosion, building collapse and fire in Brockton, Massachusetts kills 58.
• March 24 – Toastmasters International is founded by Ralph C. Smedley in Bloomington, Illinois.^[3]
• March 27 – Plumas National Forest is established.
• April 6 – Lochner v. New York: The Supreme Court of the United States invalidates New York's 8-hour-day law.
• April 6–July 19 – The 1905 Chicago Teamsters' strike; 21 people die and 416 are injured in the violence.^[4]
• May–June – John C. Merriam leads the Saurian Expedition, a paleontological research mission in northern Nevada.
• May 2-- Establishment of the first state police force in Pennsylvania
• May 6 – Klamath National Forest is established.
• May 10 – The 1905 Snyder, Oklahoma tornado destroys much of Snyder, Oklahoma, killing at least 97.
• May 12 – Gunnison National Forest is established.
• May 15 – Las Vegas, Nevada is founded when 110 acres (45 ha), in what later becomes downtown, are auctioned off.
• May 15 – Saint Tikhon's Orthodox Monastery is founded in South Canaan Township in western Wayne County, in the northeastern corner of Pennsylvania.
• May 29 – Sawtooth National Forest is established.
• June 1–October 14 – The Lewis and Clark Centennial Exposition is held in Portland, Oregon, celebrating the 100th anniversary of the Lewis and Clark Expedition.
• June 2 – Lassen National Forest is established.
• June 3 – San Juan and Payette National Forest is established.
• June 14 – Uncompahgre National Forest is established.
• June 24 – The founding convention of the Industrial Workers of the World, A radical workers union, which had great impact during the first two decades of the 20th century.

July–December

• July 11 – W. E. B. Du Bois and William Monroe Trotter establish the Niagara Movement, a precursor to the NAACP.
• July 22 – Florence Kelly delivers her landmark speech about child labor before the convention of the National American Woman Suffrage Association in Philadelphia.
• July 29 – U.S. Secretary of War William Howard Taft has talks with Prime Minister of Japan Katsura Taro. Notes from these conversations (known as the Taft–Katsura Agreement) are later found in 1924 and cause a controversy as it appears to contain U.S. recognition of Japan's claims in Korea.
• August 15 – Mexican-American prospector Pablo Valencia gets lost in the Sonoran Desert of Arizona with no water. Enduring almost eight days of dehydration, Valencia wanders until he is discovered on August 23 by anthropologist William J. McGee and McGee's Papago Indian assistant, Jose.^[5]
• August 21 – The Sequoyah Constitutional Convention takes place in Muskogee in the U.S. Indian Territory and approves a constitution for the proposed State of Sequoyah, seeking admission as the only Native American majority state in the U.S.^[6] President Roosevelt will reject the idea in favor of joining the Indian Territory with the white-ruled Oklahoma Territory to create the 46th U.S. state.
• August 23 – A. Roy Knabenshue introduces the dirigible to the skies of New York City, piloting the lighter-than-air vehicle within view of hundreds of thousands of spectators.^[7]
• September 5 – Russo-Japanese War – Treaty of Portsmouth: In New Hampshire, a treaty mediated by U.S. President Theodore Roosevelt is signed by victor Japan and Russia. Russia cedes the island of Sakhalin and port and rail rights in Manchuria to Japan.
• September 11 – 19 die and 48 are seriously injured when the Ninth Avenue Elevated train derails in Manhattan.
• October – John W. Taylor and Matthias F. Cowley resign from the Quorum of Twelve in protest, disputing the Church of Jesus Christ of Latter-day Saints' stance against polygamy that was reaffirmed in the Second Manifesto (following the Reed Smoot hearings).
• October 3 – Tonto National Forest is established.
• October 5 – The Wright Brothers' third aeroplane (Wright Flyer III) stays in the air for 39 minutes with Wilbur piloting. This is the first aeroplane flight lasting over half an hour.
• October 11 – The Institute of Musical Art, predecessor of the Juilliard School, opens in New York City.^[8]
• October 14 – The National League's New York Giants win baseball's World Series, beating the American League's Philadelphia Athletics, 2-0, in Game 5.
• November 28–29 – The massive Mataafa Storm on the Great Lakes damages or destroys 29 vessels.^[9]
• December 24 – The opera The Sho-Gun, authored by George Ade and Gustav Luders, is performed at the Grand Opera House in Seattle, Washington.^[10]
• December 30 – A bomb kills Frank Steunenberg, ex-governor of Idaho; the case leads to a trial against leaders of the Western Federation of Miners.

Undated

• Refilling of Salton Sea begins.
• Huckleberry Finn and Tom Sawyer are banned from the Brooklyn Public Library for setting a "bad example."

Ongoing

• Progressive Era (1890s–1920s)
• Lochner era (c. 1897–c. 1937)
• Black Patch Tobacco Wars (1904–1909)^[11]