[2] The county is named for Chief Justice of the United States John Marshall, who presided in the early nineteenth century.

[3] Marshall County is part of the Memphis, TN-MS-AR Metropolitan Statistical Area.

[4] As of the 2020 United States census, there were 33,752 people, 12,772 households, and 8,832 families residing in the county.

According to the census[14] of 2000, the largest ancestry groups in Marshall County were African 50.36%, English 31.87%, Scottish 7.1%, Scots-Irish 3.13%, Irish 1.2% and Welsh 1.1% There were 12,163 households, of which 34.30% had children under the age of 18 living with them, 49.60% were married couples living together, 20.10% had a female householder with no husband present, and 25.10% were non-families.

The smallest percentage margin was in 2020, when Joe Biden won the county by 3.1% over incumbent Donald Trump.