John L. "Tommy" Constant was born in Lawrence, Kansas and served in the Army during World War I before graduating from the University of Kansas with a civil engineering degree in the early 1920s. He inherited his father J.T. Constant's construction business, and Constant Construction built several significant buildings in Lawrence, including the Lawrence High School, Lawrence National Bank, Hallmark Cards, the Campanile on KU's campus, and several residential halls on campus. His company also built several private residences

Constant was also a civic and philanthropic leader in the community. He served on the City Commission and with the Chamber of Commerce, and he was involved with the Lawrence Industrial Development Company, which brought several companies to Lawrence, including Hallmark, FMC, and the Santa Fe Industrial Park. He served as a member of the University of Kansas Endowment Association (KUEA) and on the University of Kansas Athletics Board.

After his death in 1973, Constant's estate established the J.L. Constant Scholarship for Engineering School students and the J.L. Constant Distinguished Professorship fund. Other bequests from his estate established Constant Park in Lawrence.

[Information retrieved from Audio-Reader, "History - About the House," https://reader.ku.edu/history, Lawrence Modern, "Builders," https://lawrencemodern.com/builders/, and City of Lawrence, "Constant Park," https://lawrenceks.org/lprd/parks/constantpark/.]