Keith was born on Feb.16, 1929, in Mitchell, S.D., to Melvin James and Gladys (Crouch) Montgomery. As a young boy Keith moved to Huron with his parents, where he graduated from Huron High School in 1947.

After graduation he enlisted in the Army and served overseas in Japan. Keith and his brother Wayne sent home their military earnings and upon returning to Huron, learned from their proud father, they were the owners of Monte's Phillips 66. During this time, Keith met the love of his life, Marita King. The couple were married in Huron on Valentine's Day 1952. After several years, Keith began his career of 60 years in the real estate industry at McIlvaine Agency. Montgomery Real Estate & Insurance was established in 1964.

Keith knew Huron like the back of his hand and was honored to have helped so many people begin their family dreams with the purchase of a home. He developed the Gridiron Addition and Cardinal Lane areas. He was appointed to the South Dakota State Aeronautics Commission from 1968 to 1973, served as president for Greater Huron Development, S.D. Realtors, the Huron Country Club, and was named South Dakota Realtor of the Year.

Keith was at his happiest in the company of family and friends. The Black Hills is a very special place to Keith and his family, where many gatherings were held at their cabin near the Black Forest Inn. He was also instrumental in developing home building on Edelweiss Mountain in the Black Hills.

Keith is survived by his wife of 69 years Marita (King) Montgomery; children, Ann Montgomery of Wessington Springs, Keith Baird (Julie) Montgomery of Superior, WI, Beth  (Mark) Wahl of Huron, and Jean Montgomery Della Rocco of Huron; grandchildren, Joshua (Michelle) Montgomery, Erin Montgomery, Laura Montgomery, Keith Montgomery III, Adam (Sarah) Wahl, Anthony (Megan DeBoer) Wahl, Amanda (Mark) Smith, Antonia (Alex) Della Rocco and Angelina (Jae) Graffunder; 11 great-grandchildren plus one due in August.

He was preceded in death by his parents; son, Michael Montgomery; great-grandson, Josh Montgomery; brother, Wayne (Millijean) Montgomery; and sister, Marcella (Philip) Thompson.