Simplify the following text for a Grade 6 native English-speaking person.
Original: Julia Gardiner Tyler ( May 4 , 1820 or July 29 , 1820 -- July 10 , 1889 ) , second wife of John Tyler , was First Lady of the United States from June 26 , 1844 , to March 4 , 1845 .
Simplified: Julia Gardiner Tyler ( July 23 , 1820 - July 10 , 1889 ) was the second wife of John Tyler , the tenth President of the United States . She was the First Lady of the United States from June 26 , 1844 to March 4 , 1845 .