Some info on these pen pals via research by Mike Creger:

Henrietta Simpson was apparently writing home to her sister Nevada. They grew up in a family of five sisters and three brothers in Crookston. No telling what Henrietta was doing presumably in Duluth in 1910, but by 1911 she was an English major at River Falls Normal School in Wisconsin. She is pictured above, second from left, as part of the sophomore girls basketball team and Young Women’s Christian Association. Both pictures are from the 1912 yearbook. There was at least one sister in River Falls at the time.

Henrietta became an elementary teacher in River Falls and then in Minneapolis, at Hawthorne. She retired in 1959 and at some point returned to River Falls.

In 1914, a 17- or 18-year-old Nevada married Sydney Clifford Morris in Crookston. They lived in his home state of Illinois for a time and then settled in Clinton, Iowa. She was a furrier for the Skinner Furrier Company. She died in 1979 at age 82. In her obit, surviving Henrietta is mentioned as living in Clinton as well.

In the in-between years, the Simpson parents and many of the siblings ended up in Washington State. Some of the brothers spent time on the Iron Range and one, James, in Duluth up to the 1950s. The last of the children died in 1993, at age 91, Hope Ferguson. It isn’t clear when Henrietta died. Sometime between 1979 and 1988.