The first appearance of William N. St. John by name is on the 1850 Livingston County census record when he was living in a household headed by Nancy St. John. William was 19 years old, an engineer and was born in Illinois. Nancy was 60 years old and born in Virginia. Was she his mother - very possibly. Both of them may have been part of the family of an older William St. John, who is found on the 1840 Livingston County census. Ann Jane St. John, who married G.W. Burton, and P.M. St. John, who married Lavenia Wilson, were likely siblings of William N. St. John. There should have been more siblings.
William N. St. John married Serena Smith, daughter of Samuel Smith, 16 December 1856 at New Liberty, Pope County, Illinois. They were living in Livingston County in 1860 with their 2-year-old daughter, Laura. William N. continued to work on the river and was listed as a steam boat engineer.
By 1870, the St. John family had moved to Evansville, which was the center of riverboat traffic in the area. William was now listed as a river boat pilot. They did not stay long in Evansville, but returned to Livingston County before 1880.
William and Serena St. John had a number of children, including the following who appeared on the 1880 census: Laura, Jennett, William N., Joel, Alice B., Cora, Daisy, Lilly, Violet and Charles.
A small article in the River News of an Evansville newspaper recorded the death of William St. John. It stated the following: "The remains of Capt. Wm. St. John, who died at Paducah on Sunday, were taken to Smithland for burial. Capt. St. John was at one time a well known Cumberland river steamboatman. He resided in this city some years ago, and has many friends here who will be pained to learn of his death."
William N. St. John's monument marks his burial spot in Smithland Cemetery. His wife, Serena, is buried in Maplelawn Cemetery in Paducah.
Wm. N. St. John
Nov. 23, 1884
51 yr's., 9 mo's.
Buried Smithland Cemetery
 Joyce McCandless Woodyard. Livingston County, Kentucky Marriage Records Including Marriages of Freedmen, Vol. II, (Evansville, IN:Evansville Bindery) 1994, p 19-20.
 Kentucky Death Certificate #16598 (1923) of Mattie B. Hill identifies her parents as Martin [sic] St. John and Louvenia Wilson.
 Judy Foreman Lee & Carolyn Cromeenes Foss. Pope County, Illinois Marriage Books A-E 1813-1877 Vol. 1, (Evansville, IN:Evansville Bindery) 1990, p. 57
 "River News," Evansville Daily Courier, Tues., 29 November 1884, p. 3.
Published 17 September 2015, Western Kentucky Genealogy Blog, http://wkygenealogy.blogspot.com/