Charles Eli Mix was an American

United States

The United States of America is a federal constitutional republic comprising fifty states and a federal district...

 civil servant. He served as Chief Clerk of the Bureau of Indian Affairs

Bureau of Indian Affairs

The Bureau of Indian Affairs is an agency of the federal government of the United States within the US Department of the Interior. It is responsible for the administration and management of of land held in trust by the United States for Native Americans in the United States, Native American...

 from 1838 to 1868. For a brief period in 1858, Mix was Commissioner of the Bureau of Indian Affairs. During his time as Commissioner, he oversaw the signing of a treaty with the Yankton Sioux Tribe

Yankton Sioux Tribe

The Yankton Sioux Tribe of South Dakota is a federally recognized tribe of Yankton Dakota Sioux , located in South Dakota....

 of the Dakota Territory

Dakota Territory

The Territory of Dakota was an organized incorporated territory of the United States that existed from March 2, 1861, until November 2, 1889, when the final extent of the reduced territory was split and admitted to the Union as the states of North and South Dakota.The Dakota Territory consisted of...

 (present-day South Dakota

South Dakota

South Dakota is a state located in the Midwestern region of the United States. It is named after the Lakota and Dakota Sioux American Indian tribes. Once a part of Dakota Territory, South Dakota became a state on November 2, 1889. The state has an area of and an estimated population of just over...

). The Treaty of Washington

Yankton Treaty

In 1858 the United States government and the Sioux and Yankton Indian tribes reached an agreement, ceding most of eastern South Dakota to the U.S. The agreement immediately opened this territory up for settlement by whites, resulting in the establishment of an unofficial local government not...

 was signed on April 19, 1858 and ratified by the United States Senate

United States Senate

The United States Senate is the upper house of the bicameral legislature of the United States, and together with the United States House of Representatives comprises the United States Congress. The composition and powers of the Senate are established in Article One of the U.S. Constitution. Each...

 on February 16, 1859. Charles Mix County, South Dakota, organized in 1862, is named after him.

Charles Mix was born in New Haven, Connecticut

New Haven, Connecticut

New Haven is the second-largest city in Connecticut and the sixth-largest in New England. According to the 2010 Census, New Haven's population increased by 5.0% between 2000 and 2010, a rate higher than that of the State of Connecticut, and higher than that of the state's five largest cities, and...

 and married Catherine Susan Upperman on August 16, 1829. He is interred at Oak Hill Cemetery in the Georgetown

Georgetown, Washington, D.C.

Georgetown is a neighborhood located in northwest Washington, D.C., situated along the Potomac River. Founded in 1751, the port of Georgetown predated the establishment of the federal district and the City of Washington by 40 years...

 neighborhood of Washington, D.C.

Washington, D.C.

Washington, D.C., formally the District of Columbia and commonly referred to as Washington, "the District", or simply D.C., is the capital of the United States. On July 16, 1790, the United States Congress approved the creation of a permanent national capital as permitted by the U.S. Constitution....

, along with his wife and children.