Sarah Childress Polk ( September 4 , 1803 -- August 14 , 1891 ) was the wife of the 11th President of the United States , James Polk , serving as First Lady of the United States from 1845 to 1849 .
Sarah Childress Polk ( September 4 , 1803 - August 14 , 1891 ) was the wife of the US President James K. Polk . She was the First Lady of the United States from March 4 , 1845 to March 3 , 1849 .