Thanks to a lady (Carolyn Elmore) from the Smyth County genealogy page on facebook, I have now some other names to research. In the 1860 census of Campbell County, there was an 1790 born, Ann Powers. Also in the home was a Margaret Powers, aged 55. Could this be the missing female from the 1830 census, could be. I just cannot find her in the 1850 census anywhere.
In the 1870 census of Campbell County is the following family:
MCCORMICK, Pleas 49
George W. 21
James M. 17
Daniel M. 7
POWERS, SA 80 (born 1790)
Now, it is possible that the SA Powers is our Ann, but this Margaret is not the same Margaret in the 1860 censs as Pleas McCormick married Margaret Missouri Powers Jan. 29, 1949, But, who does this Margaret Missouri Powers belong to and what happened to the Margaret Powers from the 1860 census?