April 4 – Los Angeles, California is incorporated as a city.
April 15 – San Francisco, California is incorporated as a city.
April 19 – Clayton-Bulwer Treaty is signed by the United States and Great Britain, allowing both countries to share Nicaragua and not claim complete control over the proposed Nicaragua Canal.
July 9: Vice President Millard Fillmore becomes President with the death of President Taylor
July 9 – President Zachary Taylor dies in office; Vice President Millard Fillmore becomes the 13th President of the United States.
September 9
California is admitted to the Union as the 31st state (see History of California).
Utah Territory is established.
New Mexico Territory is organized by order of the U.S. Congress.
September 18 – The Fugitive Slave Act of 1850 is passed by the U.S. Congress.
Zachary Taylor (November 24, 1784 – July 9, 1850) was the 12th President of the United States, serving from March 1849 until his death in July 1850. Taylor previously was a career officer in the United States Army, rose to the rank of major general and became a national hero as a result of his victories in the Mexican–American War. As a result, he won election to the White House despite his vague political beliefs. His top priority as president was preserving the Union, but he died sixteen months into his term, before making any progress on the status of slavery, which had been inflaming tensions in Congress.