February 15 – USS Maine explodes and sinks in Havana harbor, Cuba, killing 266 men. Popular opinion blames Spain and helps precipitate the Spanish–American War.
February 22 – Naoum Mokarzel establishes Al-Hoda which will become the longest-running Arabic newspaper in the U.S.
March 28 – After an investigation, the U.S. Navy publicly concludes that USS Maine was sunk by a mine, further pushing sentiment towards war.
March 30 – The 5.8–6.4 MwMare Island earthquake shook the San Francisco Bay Area with a maximum Mercalli intensity of VIII (Severe), causing $350,000 in damage.
April–June
April 5 – Annie Oakley promotes the service of women in combat situations with the United States military. On this day, she writes a letter to President McKinley "offering the government the services of a company of 50 'lady sharpshooters' who would provide their own arms and ammunition should war break out with Spain."[2] In the history of women in the military, there are records of female U.S. Revolutionary and Civil War soldiers who enlisted using male pseudonyms, but Oakley's letter represents possibly the earliest political move towards women's rights for combat service in the United States military.
April 20 – President William McKinley signs a Joint Resolution with Cuba and a declaration of War against Spain, beginning the Spanish–American War. The declaration is accepted five days later.
April 25 – Spanish–American War: The United States declares war on Spain; the U.S. Congress announces that a state of war has existed since April 21 (later backdating this one more day to April 20).
April 29 – Union Razor Company, which today is known as KA-BAR Knives, founded in Tidioute, Pennsylvania.
As a result of the merger of several small oil companies, John D. Rockefeller's Standard Oil Company controls 84% of the United States's oil and most American pipelines.
September 28 – Thomas F. Bayard, U.S. Senator from Delaware from 1869 to 1885 and Secretary of State from 1885 to 1889 (born 1828)
October 12 – John M. Forbes, merchant, philanthropist and abolitionist, president of the Michigan Central and Chicago, Burlington and Quincy Railroads (born 1813)