James Edward Deninger was born February 9, 1943, in Manly, Iowa the son of Joseph and Justine (Kisch) Deninger. He graduated from North Central High School in 1961. He then attended North Iowa Junior College receiving his degree in drafting. He was a member of the Iowa National Guard during this time. On May 14, 1966, he married Isolde Raab in Marshalltown. The couple made their home in Marshalltown raising their family and Jim working for Fisher Controls as a manager for many years before retiring in 1990.

He was active in city government for many years serving as a councilman as well as sitting on many committees. He stayed involved in politics on all levels, was a staunch supporter of individual liberty, and an advocate of personal responsibility, accountability and held a strong sense of family values.

Jim enjoyed the outdoors, hunting, fishing, golfing and spending time teaching his boys. His family includes his wife, Isolde, their three children, Mike Deninger, (Beth Deninger), William Deninger, (Jeana Deninger), Paul Deninger (Jennifer Deninger); seven grandchildren Reed, Madeline, Andrew, Katherine, Jacob, Michelle, and Matthew. He has one surviving sibling, Joanne Froeschle. Jim was preceded in death by his parents, and two siblings, Jerry and Barbara.