Susanna(h)Catherine Harry was born c. 1800 in Rockingham Co., VA. She was the daughter of John Harry, Sr. and Elizabeth Saylor. The family had moved from Hagerstown, Washington Co., MD to Rockingham Co., VA in the late 1700's. Sarah's siblings include Samuel Harry, Elizabeth Harry who married Joseph Sively (and also moved to Christian Co., KY), Peter Harry, Sarah Harry who married John J. Swisher, Ann Kemper Harry, Margaret (or Peggy) Harry who married Jesse Thompson, John Harry Jr., Eli Harry, David Harry and Jacob Harry.
I agree with you the 1850 Pettis Co., MO Census is an obvious error as she married in 1820. I think it should have read 50, instead of 40.