. Named for its extralegal predecessor county, Jefferson County , which in turn was named in honor of Thomas Jefferson , the author of the Declaration of Independence and the third President of the United States . &&&&&&&&&0526994.&&&&&0 526,994 &&&&&&&&&&&02001.670000 2,001.67 sq mi ( &&&&&&&&&&&05184.&&&&&0 5,184 km 2 ) State map highlighting Jefferson County Kiowa County