1855 in the United States

Events from the year 1855 in the United States.

Federal government

 * President: Franklin Pierce (D-New Hampshire)
 * Vice President: vacant
 * Chief Justice: Roger B. Taney (Maryland)
 * Speaker of the House of Representatives: Linn Boyd (D-Kentucky)
 * Congress: 33rd (until March 4), 34th (starting March 4)

{| class="wikitable collapsible collapsed" ! Governors and lieutenant governors

Governors
• Governor of Alabama: John A. Winston (Democratic)

• Governor of Arkansas: Elias Nelson Conway (Democratic)

• Governor of California: John Bigler (Democratic)

• Governor of Connecticut: Henry Dutton (Whig) (until May 2), William T. Minor (Know Nothing) (starting May 2)

• Governor of Delaware: William H. H. Ross (Democratic) (until January 16), Peter F. Causey (Know Nothing) (starting January 16)

• Governor of Florida: James E. Broome (Democratic)

• Governor of Georgia: Herschel V. Johnson (Democratic)

• Governor of Illinois: Joel Aldrich Matteson (Democratic)

• Governor of Indiana: Joseph A. Wright (Democratic)

• Governor of Iowa: James W. Grimes (Whig)

• Governor of Kentucky: Lazarus W. Powell (Democratic) (until September 4), Charles S. Morehead (Know Nothing) (starting September 4)

• Governor of Louisiana: Paul Octave Hébert (Democratic)

• Governor of Maine: William G. Crosby (Whig) (until January 3), Anson Morrill (Republican) (starting January 3)

• Governor of Maryland: Thomas W. Ligon (Democratic)

• Governor of Massachusetts: Emory Washburn (Whig) (until January 4), Henry Gardner (Know Nothing) (starting January 4)

• Governor of Michigan: Andrew Parsons (Democratic) (until January 3), Kinsley S. Bingham (Republican) (starting January 3)

• Governor of Mississippi: John J. McRae (Democratic)

• Governor of Missouri: Sterling Price (Democratic)

• Governor of New Hampshire: Nathaniel B. Baker (Democratic) (until June 7), Ralph Metcalf (Know Nothing) (starting June 7)

• Governor of New Jersey: Rodman M. Price (Democratic)

• Governor of New York: Myron H. Clark (Whig) (starting January 1)

• Governor of North Carolina: Warren Winslow (Democratic) (until January 1), Thomas Bragg (Democratic) (starting January 1)

• Governor of Ohio: William Medill (Democratic)

• Governor of Pennsylvania: William Bigler (Democratic) (until January 16), James Pollock (Whig) (starting January 16)

• Governor of Rhode Island: William W. Hoppin (Whig)

• Governor of South Carolina: James Hopkins Adams (Democratic)

• Governor of Tennessee: Andrew Johnson (Democratic)

• Governor of Texas: Elisha M. Pease (Unionist)

• Governor of Vermont: Stephen Royce (Whig)/(Republican)

• Governor of Virginia: Joseph Johnson (Democratic)

• Governor of Wisconsin: William A. Barstow (Democratic)

Lieutenant governors
• Lieutenant Governor of California: Samuel Purdy (Democratic)

• Lieutenant Governor of Connecticut: Alexander H. Holley (Whig) (starting January 4), William Field (Free Soil) (starting January 4)

• Lieutenant Governor of Illinois: Gustavus Koerner (Democratic)

• Lieutenant Governor of Indiana: Ashbel P. Willard (Democratic)

• Lieutenant Governor of Kentucky: vacant (until September 4), James Greene Hardy (Know Nothing) (starting September 4)

• Lieutenant Governor of Louisiana: Robert C. Wickliffe (Democratic)

• Lieutenant Governor of Massachusetts: William C. Plunkett (political party unknown) (until month and day unknown), Simon Brown (political party unknown) (starting month and day unknown)

• Lieutenant Governor of Michigan: George Griswold (Democratic) (until month and day unknown), George Coe (Republican) (starting month and day unknown)

• Lieutenant Governor of Missouri: Wilson Brown (Democratic) (until August 27), vacant (starting August 27)

• Lieutenant Governor of New York: Henry Jarvis Raymond (Whig) (starting January 1)

• Lieutenant Governor of Ohio: James Myers (Democratic)

• Lieutenant Governor of Rhode Island: John J. Reynolds (political party unknown) (until month and day unknown), Anderson C. Rose (political party unknown) (starting month and day unknown)

• Lieutenant Governor of South Carolina: Richard de Treville (Democratic)

• Lieutenant Governor of Texas: David Catchings Dickson (Democratic) (until month and day unknown), Hardin Richard Runnels (Democratic) (starting month and day unknown)

• Lieutenant Governor of Vermont: Ryland Fletcher (Republican)

• Lieutenant Governor of Virginia: Shelton Leake (Democratic)

• Lieutenant Governor of Wisconsin: James T. Lewis (Republican)
 * }

Events

 * January – Klamath and Salmon River War: In Klamath County, California, hostility between settlers and the local Native Americans becomes violent. The California State Militia and U.S. Army intervene, ending the war in March.
 * January 23 – The first bridge over the Mississippi River opens in what is now Minneapolis, Minnesota (a crossing made today by the Hennepin Avenue Bridge).
 * January 26 – The Point No Point Treaty is signed in the Washington Territory.
 * February 12 – Michigan State University (the "pioneer" land-grant college) is established.
 * February 15 – The North Carolina General Assembly incorporates the Western North Carolina Railroad to build a rail line from Salisbury to the western part of the state.
 * February 22 – Pennsylvania State University is founded as the Farmers' High School of Pennsylvania.
 * March 3 – The U.S. Congress appropriates $30,000 to create the U.S. Camel Corps.
 * March 16 – Bates College is founded by abolitionists in Lewiston, Maine.
 * March 30 – Elections are held for the first Kansas Territory legislature. Missourian 'Border Ruffians' cross the border in large numbers to elect a pro-slavery body.
 * April – Cincinnati riots of 1855: Tension between nativists and German-American immigrants in Cincinnati breaks out into territorial street fighting on election day.
 * May 17 – The Mount Sinai Hospital is dedicated (as the Jews' Hospital) in New York City; it opens to patients on June 5.
 * June 6 – Portland Rum Riot: A crowd gathers at a storehouse believed to hold alcohol in Portland, Maine. The militia is called in and fires on the crowd to disperse the crowd, killing one person.
 * June 28 – The Sigma Chi fraternity is founded at Miami University in Oxford, Ohio.
 * July 1 – Quinault Treaty signed, Quinault and Quileute cede their land to the United States.
 * July 2 – The Kansas Territorial Legislature convenes in Pawnee and begins passing proslavery laws.
 * July 4 – Walt Whitman's poetry collection Leaves of Grass is published in Brooklyn.
 * July 6 – The Kansas Territorial Legislature meets for the last time in Pawnee, voting to relocate to Shawnee, closer to the border of slave state Missouri.
 * July 16 – U.S. Indian commissioner Isaac Stevens signs the Hellgate treaty with Native Americans living in modern-day western Montana.
 * August 6 – Bloody Monday: Protestant mobs attack Irish and German Catholics on an election day in Louisville, Kentucky, causing 22 deaths.
 * September 3 – First Sioux War: Battle of Ash Hollow – U.S. forces defeat a band of Brulé Lakota in present-day Garden County, Nebraska.
 * October 5 – Yakima War: Battle of Toppenish Creek – In the Yakima River Valley, a band of Yakama warriors forces a company of U.S. soldiers to retreat in the first battle of the War.
 * October 28–31 – First Fiji expedition: The U.S. Navy dispatches the USS John Adams to Viti Levu, Fiji, to protect American interests. One American sailor is killed and two Marines are wounded.
 * November 1 – 31 people are killed in the Gasconade Bridge train disaster in Missouri.
 * November 9–10 – Yakima War: Battle of Union Gap – American soldiers attack a Yakama village, forcing the village to retreat.
 * November 21 – Large-scale Bleeding Kansas violence begins with events leading to the Wakarusa War between antislavery and proslavery forces.

Ongoing

 * Samuel Colt incorporates his business as the Colt's Patent Firearms Manufacturing Company and opens a new factory, the Colt Armory, in Hartford, Connecticut. Horace Smith and Daniel B. Wesson form the Volcanic Repeating Arms Company in New England.
 * California Gold Rush (1848–1855)
 * Bleeding Kansas (1854–1860)
 * Third Seminole War (1855–1858)
 * Yakima War (1855–1858)

Births

 * February 4 – George Cope, painter (died 1929)
 * February 23 – Jonathan Bourne, Jr., U.S. Senator from Oregon from 1907 to 1913 (died 1940)
 * June 14 – Robert M. La Follette, U.S. Senator from Wisconsin (died 1925)
 * June 17 – Janet Cook Lewis, portrait painter, librarian, and bookbinder (died 1947)
 * July 29 – Bowman Brown Law, politician (died 1916)
 * August 4 – Jay Hunt, film director (died 1932)
 * September 2 – M. Hoke Smith, U.S. Senator from Georgia from 1911 to 1920 (died 1931)
 * October 21 – Howard Hyde Russell, temperance activist (died 1946)
 * October 24 – James S. Sherman, 27th vice president of the United States from 1909 to 1912 (died 1912)
 * October 26 – Jessie Wilson Manning, American author and lecturer
 * November 5 – Eugene V. Debs, union leader (died 1926)
 * November 6 – Annie Keeler, early woman physician (died 1927)
 * December 10 – August Spies, labor activist and newspaper editor (died 1887)
 * December 28 – John William Wood, Sr., North Carolinan politician, founder of Benson, North Carolina (died 1928)

Deaths

 * March 8 – William Poole, founder of the street gang the Bowery Boys and leader of the Know Nothing political movement (born 1821)
 * March 25 – Thomas Fitzgerald, United States Senator from Michigan from 1848 till 1849. (born 1796)
 * March 28 – William S. Archer, United States Senator from Virginia from 1841 till 1847. (born 1789)
 * May 7 – Walter T. Colquitt, United States Senator from Georgia from 1843 till 1848. (born 1799)
 * June 29 – John Gorrie, physician, scientist, inventor, and humanitarian (born 1803)
 * August 18 – Thomas Metcalfe, United States Senator from Kentucky from 1848 till 1849. (born 1780)