Mississippi ( ) is a state in the Southeastern region of the United States, bordered to the north by Tennessee; to the east by Alabama; to the south by the Gulf of Mexico; to the southwest by Louisiana; and to the northwest by Arkansas. Mississippi's western boundary is largely defined by the Mississippi River, or its historical course. Mississippi is the 32nd largest by area and 35th-most populous of the 50 U.S. states and has the lowest per-capita income in the United States. Jackson is both the state's capital and largest city. Greater Jackson is the state's most populous metropolitan area, with a population of 591,978 in 2020.

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 slaves accounted for 55% of the state population. Mississippi declared its secession from the Union on January 9, 1861, and was one of the seven original Confederate States, which constituted the largest slaveholding states in the nation. Following the Civil War, it was restored to the Union on February 23, 1870. From the end of the Civil War to the 1960s, Mississippi was dominated by socially conservative and segregationist Democrats dedicated to upholding white supremacy. Mississippi became the site of many prominent events during the civil rights movement, including the Ole Miss riot of 1962, the 1963 assassination of Medgar Evers, and the 1964 Freedom Summer murders.

Mississippi ranks among the highest of U.S. states in religiosity and among the lowest in measures of health, education, development, and income. Top industries in Mississippi today are agriculture and forestry. Mississippi produces more than half of the country's farm-raised catfish, and is also a top producer of sweet potatoes, cotton and pulpwood. Others include advanced manufacturing, utilities, transportation, and health services. Mississippi is almost entirely within the east Gulf Coastal Plain, and generally consists of lowland plains and low hills. The northwest remainder of the state consists of the Mississippi Delta. Mississippi's highest point is Woodall Mountain at 807 feet (246 m) above sea level adjacent to the Cumberland Plateau; the lowest is the Gulf of Mexico. Mississippi has a humid subtropical climate classification.