Johnson kept a daily diary for sixteen years, beginning in 1835 and ending with his
death in 1851. This diary followed the life of a free man of color,with daily entries about being a family man of ten children, his daily outdoor activities, and also told what it was like being a successful businessman.
William Johnson built a three story brick house in Natchez, MS where he moved his large family into in 1841. The downstairs space was occupied by commercial property, quarters for his servants, and housed livestock on the property. After his death, his family continued living in the house and eventually was purchased by the National Park Service in 1990.