Mary Gage Peterson was born in New Hampshire on October 2, 1844 as Mary Augusta Gage. Her parents were Tenney Kimball Gage and Mary Sophiah Kimball. When she was a child, the family moved to Boston and Mary Gage was allowed to "roll her hoop one time per day around Boston Common."

She attended Mt. Holyoke College in South Hadley, MA and graduated from the State Normal School of New York, now known as the University at Albany, SUNY. Shortly after graduating, she met Pehr Peterson; they married on October 26, 1865.

Marriage to Pehr Peterson and the Peterson Nursery

After getting married, they moved to Illinois - about 10 miles northwest of downtown Chicago and 3 miles west of Lake Michigan. They lived in a large house near what is now the northwest corner of Kimball and Peterson Avenues. This area was called the "Peterson Nursery" or the "Rosehill Nursery."

Slowly, as the tree nursery and related business grew, Mary Gage Peterson rose into leadership roles in a variety of educational and civic organizations.