1917 WWI Draft Registration 5 June 1917: Robert Lewis Frederick Hinkle, born 1 Sep 1886 in Stillwater, Minnesota, is a mining engineer in Crosby Minnesota and claims exemption due to his dependent wife and child under age 12. He is tall, of medium build with brown eyes and dark hair.
1920 U.S. Census Crosby, Crow Wing, Minnesota: Robert L.F. Hinkle age 33 and wife Marie age 32 lived on Main Street East with son Robert L.F. Jr. age 6. Robert was born in Minnesota, his father was born in Missouri and his mother in Massachusetts. Marie was born in Minnesota, her father in Iowa and her mother in Illinois. Robert Jr was born in Minnesota. Robert is mining engineer in an iron mine.
1930 U.S. Census Crosby, Crow Wing, Minnesota: Robert L.F. Hinkle age 43 and wife Marie age 42 lived at 202 Main Street with son Robert Jr. age 16 and daughter Phyllis M. age 18 (perhaps an error and should be 8 since not listed in 1920 census). Robert was born in Minnesota, his father was born in Missouri and his mother in Minnesota. Marie was born in Minnesota, her father in Iowa and her mother in Illinois. Both children were born in Minnesota. Robert is mining engineer in an iron mine. Robert was age 26 and Marie age 25 at marriage.
Living in Crosby, Minnesota, in 1931 (noted in his father's obituary)