Donald James Mercer, 84, died Aug. 16, 2026. Don was born April 30, 1942, the fourth and youngest child of Dorothy (Lechnir) and Harvey Mercer in Prairie du Chien. He graduated from Campion Jesuit High School in Prairie du Chien, and attended the University of Wisconsin, earning a Bachelor of Science degree in Civil Engineering. He then moved to Lansing, Michigan and worked his entire career at the Michigan Department of Transportation, mostly in the field of traffic safety.

At MDOT Don became enamored with a cute young secretary, Mary Jo Isbell. After a classic interoffice romance, they wed on August 23, 1969 and enjoyed a marriage of just over 50 years until Mary Jo passed away on November 10, 2019. Mary Jo and Don had three children, daughter Wendy and sons Robert (Lisa) and Thomas (Peter).

Don earned a Masters degree in Civil Engineering at Michigan State University and was a registered Professional Engineer. He was a past-president of the Lansing Jackson Branch and of the Michigan Section of the American Society of Civil Engineers, and was the last remaining active charter member of the Transportation Toastmasters club. He won national awards with both organizations.

He was a long-time member of St. Mary Cathedral parish in Lansing and over the years held various volunteer positions for the parish. In retirement, he served as a tax preparer for the AARP Tax Consulting for the Elderly. Don was an ardent Lugnuts fan since the team came to Lansing and was an active member of the Lugnuts Booster Club.

He is survived by his children and by his sister Marianne Welsh, his brother Jack, and his sister Janet Loforte.

Don was a man who deeply loved his family and loved spending time with them. He always had kind words to say about everyone he met. Don was a quiet man, gentle and kind, who preferred working in the background to help make other peoples’ lives better.

Mass of Christian Burial will be held at 10 a.m. Friday, Aug. 21, at St. Mary Cathedral, 219 Seymour Ave., Lansing, with the Rite of Committal in Evergreen Cemetery. Visitation will be at the Estes-Leadley Greater Lansing Chapel from 6-8 p.m. Thursday. Online condolences may be left for his family at www.EstesLeadley.com.