Leon was born in Fairfield, Idaho to Ivan and Alberta Nielson on August 16, 1936. He went to school in Wendell and worked for his brother as a well driller.
Leon married Caroline Wilson, on February 13, 1956 and they moved to Pasco, where Leon went to work at his father's service station. Later they moved to Seattle and Leon went to work for Boeing. Two children were born while they were living in Seattle. The family moved back to Wendell and three more children joined the family and Leon went back to work drilling wells. When the family moved to Homedale,Leon worked between drilling and on a cinnabar mine.
In 1966 the family moved to Grand View where Leon continued drilling, and enjoyed fishing, hunting and his pontoon boat very much. Leon was also part owner of a farm with Nemco and worked for the City of Grand View for about eighteen years until his retirement. After Leon's retirement he and Caroline took two trips to Israel, which were both wonderful experiences for him.
Leon is survived by his wife Caroline, a son Terry and his wife Drena Nielson all of Grand View, a son Curtis and his wife LaRue Nielson, a son Daniel and his wife Christy Nielson all of Glenns Ferry, a son Calvin Nielson of Boise, a daughter Mona Nielson of Florida, 13 grandchildren and 14 great-grandchildren. Leon is also survived by his sisters; Lila Simmonds of Washington, Neta Pepper of Boise and Arva Ruhter of Arizona. He was preceded in death by his parents, one brother and one sister.