I cannot be certain, but I am quite confident the information, below, is for the recipient of this cover.  

The 1880 census of Richmond Township lists John K. Rothermel (age 44), Susan (age 36) and Florence (age 4).  John is a “Farmer.” 

The 1900 census of Maxatawny Township lists a Florence Rothermel (born Jun 1875).  It appears she is living in a dorm or other housing at the Keystone State Normal School.  Her occupation states, “English Brancher.”   

The 1910 census of Philadelphia Ward 24 lists Florence Rothermel (age 34, single, boarder) as a “Teacher.” 

The 1930 census of Philadelphia shows Florence (age 54, single, lodger) as a “Teacher” in “Public School.” 

Florence never married.  She is buried at Becker’s St. Peter’s Lutheran Church Cemetery in Molltown.  Her death certificate states she was born on 22 Jun 1875 in Richmond Township, died 27 May 1963 in Lancaster County and was the daughter of John K. Rothermel (1835-1908) and Susan E. Peters (1843-1930).