I have been recently researching Jefferson County, Mississippi again and felt I should share this:

Mississippi discontinued Counties:

Bainbridge – Formed from Lawrence and Wayne Counties renamed Covington County
Sumner – Formed in 1874 from Montgomery and Choctaw Counties, renamed Webster in 1882.
Pickering – Formed in 1799 from the Natchez District, renamed Jefferson County in 1802.
Colfax – Formed in 1871, renamed Clay County in 1876.

http://www.mymississippigenealogy.com/index.htm#

Ed Adams