Note - Lucy Clark's first cousin.

Courtship and marriage - Clark married Julia Hancock on January 5, 1808, at Fincastle, Virginia, and they had five children:[11] Meriwether Lewis Clark, Sr. (1809-1881) named after his friend Meriwether Lewis; William Preston Clark (1811-1840); Mary Margaret Clark (1814-1821); George Rogers Hancock Clark (1816-1858), named after Clark's older brother; and John Julius Clark (1818-1831). After Julia's death in 1820, Wm. Clark married her first cousin Harriet Kennerly Radford, and they had three children: Jefferson Kearny Clark (1824-1900); Edmund Clark (1826-1827); and Harriet Clark (dates unknown; died as child). His second wife died in 1831.

-------------------- After William Clark's 1st wife Julia died in 1820 he married her 1st cousin, Harriet.