Leavenworth () is the county seat of and the largest city in Leavenworth County, Kansas, United States. As of the 2020 census, the population of the city was 37,351.
History
Leavenworth, founded in 1854, was the first city incorporated in the territory of Kansas. The city developed south of Fort Leavenworth, which was established as Cantonment Leavenworth in 1827 by Colonel Henry Leavenworth. Its location on the Missouri River attracted refugee African-American slaves in the antebellum years, who were seeking freedom from the slave state of Missouri across the river. Abolition supporters helped them find refuge. In the years before the Civil War, Leavenworth was a hotbed of anti-slavery and pro-slavery agitation, often leading to open physical confrontations on the street and in public meetings.
On April 3, 1858, the "Leavenworth Constitution" for the state of Kansas was adopted here. Although the federal government never approved this early version of the state constitution, it was considered one of the most radical of the four constitutions drafted for the new territory because it recognized freed black people as citizens.
Refugee African Americans continued to settle in the city during the war. By 1865, it had attracted nearly one-fifth of the 12,000 black people in the state. In 1866, the 10th Regiment of Cavalry, an all-black unit within the U.S. Army, was stood up at Fort Leavenworth. Charles Henry Langston was an African-American leader from Ohio who worked and lived in Leavenworth and northeastern Kansas in the Reconstruction era and afterward. In Kansas, Langston worked for black suffrage and the right of African Americans to sit on juries, testify in court, and have their children educated in common schools. African Americans gained suffrage in 1870 after passage of the federal 15th constitutional amendment, and the legislature voted for their right to sit on juries in 1874. He protested his innocence to the end. An inquest concluded he had been killed by "persons unknown".
His family refused to claim his body for burial. His father Alfred Alexander, an exoduster, said "The people have mutilated him, now let them bury him." (The National Association for the Advancement of Colored People (NAACP) was founded a few years later, and absorbed most members of the AAC.)
In 1972 Benjamin Day became the city's first African-American mayor. Day had been elected to the City Commission one year earlier. Leavenworth appoints its mayor from among the members of the commission, and Day was named mayor in 1971. Day was a former educator and principal in Leavenworth.
Fort Leavenworth was located outside the city limits until its territory was annexed by the city on April 12, 1977.
In 2008, an underground series of "vaults" was found in the city, apparently built during the late 19th century.
Geography
thumb|right|upright|Leavenworth is on the west bank of the Missouri River
Leavenworth is located in northeastern Kansas at the junction of U.S. Route 73 and Kansas Highway 92 (K-92), Leavenworth is northwest of downtown Kansas City, south-southeast of Omaha, and northeast of Wichita. Four small tributaries of the river flow generally east through the city. From north to south, these are Quarry Creek, Corral Creek, Three Mile Creek, and Five Mile Creek.
According to the United States Census Bureau, the city has a total area of , of which is land and is water. Fort Leavenworth occupies the northern half of the city's area.