Born in Bowling Green, Kentucky, Denning is a graduate of the Kentucky State Police Academy, the second Black Trooper in the history of the Kentucky State Police. While serving as a Kentucky State Police trooper, he became the first black ever elected to public office in Bowling Green and Warren County as member of the Bowling Green School Board in 1975. In 1991, Denning became the first black City Commissioner in Bowling Green. In January 2011, Denning served as the pro tem mayor. Denning became mayor within the thirty-day period after the resignation of Elaine Walker who was set to become the Secretary of State for Kentucky.
- "Notable Kentucky African Americans Database". University of Kentucky. Retrieved 16 May 2011.
- Highland, Deborah. "Serve & Protect". April 26, 2011. Bowling Green Daily News. Retrieved 16 May 2011.
- Robinson, Andrew. "Commissioner Joe Denning will become city's first black Mayor. Denning lost the Mayor's race in 2011 and was re-appointed to the Commission in November. He ran for the Commissioner seat in November 2012 an won for a two year term. mayor". January 7, 2011. Bowling Green Daily News. Retrieved 16 May 2011.