Robert Brooks Cullum, cofounder of Tom Thumb-Page Food Stores and civic leader, son of Ashley Wilson and Eloise (Brooks) Cullum, was born on May 10, 1912, in Dallas. While attending North Dallas High School he was quarterback on the football team despite his short height of 5'6". He continued as quarterback during his single term at Kemper Military School in Missouri before transferring to Southern Methodist University, where he received his bachelor of science in journalism in 1933. Cullum planned on a career in advertising, but the Great Depression left him unable to find a job. Therefore, he went into his father's wholesale food business after graduation. On July 6, 1934, he married Dorothy Rogers; they had four children.
Cullum and his brother Charles both worked in the small family business his father had started. In the 1940s their biggest client was Toro Food Stores, a failing food chain. The owner fled to South America owing the Cullums $200,000. In 1948 the Cullum brothers took over the Toro Food Chain in order to avoid bankruptcy, took out a loan, and renamed the chain Tom Thumb. The first advertising, designed by Bob Cullum, was placed in the Dallas Morning News in 1948. In 1966 the brothers bought out Page Drug Stores. Eventually the two chains merged as Tom Thumb-Page. In 1981 the chain included 132 grocery stores, meat-packing plants, and a wholesale business that supplied restaurants and hotels.
In 1962 Cullum received the Linz Award for civic service to Dallas and the Brotherhood Citation of the National Conference of Christians and Jews. In 1964 he was named the Dallas Press Club's Headliner of the Year. He was president of the Dallas Chamber of Commerce and in 1964–65 was one of three negotiators responsible for the Dallas-Fort Worth Regional Airport (now Dallas-Fort Worth International Airport). From the 1950s he was active on the board of the State Fair of Texas; he served as president of the board from 1967 to 1979. In 1972 he was president of the Dallas Citizens Council. In October of 1979 the Dallas City Council named a street near Fair Park Robert B. Cullum Boulevard.
Cullum served on the boards of many businesses, including Dallas Power and Light Company, the Dr Pepper Company, and Republic National Bank of Dallas. He was director emeritus of Dallas Federal Savings and Loan Association and the director of the Dallas Council of World Affairs, the American Red Cross, the Dallas Zoological Society, and the Texas Research Foundation. He was a trustee of the Callier Center for Communication Disorders and of the Southwestern Medical Foundation (see UNIVERSITY OF TEXAS SOUTHWESTERN MEDICAL CENTER, DALLAS). He was a member of the board of governors of Southern Methodist University and the Dallas-Fort Worth airport. He belonged the National Association of Food Chains and the Super Market Institute, of which he was president in 1966–67. He was a member of the Cotton Bowl Athletic Association and the Southern United Methodist Alumni Association. He was a Methodist and belonged to a variety of clubs, including the Chaparral, City, Koon Kreek, and Dallas country clubs. He died on December 11, 1981, in Dallas and is buried in Hillcrest Mausoleum.