The son of Scottish immigrants, Harold Gregor was born in Detroit, MI, and earned his PhD from Ohio State University. He served as professor of art history and painting at three other colleges and universities before joining Illinois State University in 1970, and retired from there in 1995.

He became known as the founder of the Heartland School of landscape painters and had work displayed at prominent locations and exhibitions internationally. He received a host of awards and grants and was represented by galleries in Chicago, Santa Fe, New York City, Milwaukee as well as having his own gallery in downtown Bloomington.

He was active in a variety of local art and civic organizations. He had two daughters, Katherine and Melissa Gregor, with his first wife Sandra Jennings Gregor, and a long marriage to Marlene Pierce Rittenhauer Gregor. This collection includes announcements of gallery openings and workshops, magazine articles, exhibition catalogs, etc.