Knox County was formed in 1845 from Scotland County
Knox County was named after General Henry Knox of Revolutionary War fame and the first Secretary of War under George Washington.  The area was first part of Scotland County but by 1843 was populated enough to become a county and became so in 1845.

Upon the organization, at the first session of the county court, in April 1845, the county was divided into four municipal townships, Benton Center, Fabius and Salt River.

Two additional townships were formed before 1860, according to the Goddspeed history (pages 741 and 742).  Greensburg Township (Congressional Township 63, Range 13 west) was orgainzed May 3, 1859.  Jeddo Township (Congressional Township 61, Range 10 West) was orgainzed in October 1859.