Stephen P. Barnum served in the US Civil War as a Private in Company "K", 6th Regiment, Michigan Volunteer Cavalry. He suffered from chronic diarrhea, resulting disease of the rectum and rheumatism, and received a pension as an Army Invalid.
In the 1880 US Census for District 36, Thornapple, Barry County, Michigan the family of Stephen P. Barnum was enumerated as follows:
Dwelling #216; Family #217
Barnum, Philander; W; M; 36; Married; Laborer; b. Michigan; Father b. New York; Mother b. Canada
Barnum, Abigail; W; F; 32; Wife; Married; Keeping house; b. Pennsylvania; Both parents b. New York
Barnum, Franklin; W; M; 12; Son; Single; At school; Attended school within the year; b. Michigan; Father b. Michigan; Mother b. Pennsylvania
Barnum, Lottie; W; F; 10; Daughter; Single; At school; Attended school within the year; b. Michigan; Father b. Michigan; Mother b. Pennsylvania
Barnum, Fidelia; W; F; 7; Daughter; Single; At school; Attended school within the year; b. Michigan; Father b. Michigan; Mother b. Pennsylvania
Barnum, Ernest; W; M; 4; Son; Single; b. Michigan; Father b. Michigan; Mother b. Pennsylvania
Barnum, Lydia; W; F; 2; Daughter; Single; b. Michigan; Father b. Michigan; Mother b. Pennsylvania
Barnum, Bertha; W; F; 1/12; b. April; Daughter; Single; b. Michigan; Father b. Michigan; Mother b. Pennsylvania