On December 10 , 1817 , Mississippi became the 20th state admitted to the Union . By 1860 , Mississippi was the nation 's top cotton producing state and enslaved persons accounted for 55 % of the state population . Mississippi declared its secession from the Union on March 23 , 1861 , and was one of the seven original Confederate States . Following the Civil War , it was restored to the Union on February 23 , 1870 . Until the Great Migration of the 1930s , African Americans were a majority of Mississippi 's population . Mississippi was the site of many prominent events during the American Civil Rights movement , including the 1962 Ole Miss riots , the 1963 assassination of Medgar Evers , and the 1964 Freedom Summer murders . Mississippi frequently ranks low among states in measures of health , education , poverty , and development . In 2010 , 37.3 % of Mississippi 's population was African American , the highest percentage for any state
Freedom Summer murders
Murders of Chaney, Goodman, and Schwerner
Mississippi