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 Rhode Island: John J. Reynolds (political party unknown) (until month and day unknown), Anderson C. Rose (political party unknown) (starting month and day unknown)
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.[1]
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 stateMissouri.
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.[2]