After buying his first truck in 1949, a Chevrolet Maple Leaf, Roland Mullen persevered through two decades of economic growth and contraction. He hauled gravel for $3.50 per hour in 1950. By the mid-50s, he was operating three trucks. In the early 1960s, amid an economic downturn, Roland drove for Nodwell Brothers in Alaska. When the economy improved, he became independent once more, buying his first Kenworth in 1965 and a second Kenworth three years later.
The fleet continued to expand throughout the 1970s. In 1979, Mullen had authority to transport across the Canada-U.S. border and the fleet size increased to 40 trucks. In the 1980s, Mullen relocated from Calgary to Aldersyde, south of the city. It operated from a modified mobile home. Mullen began to computerize its operations and in 1983, established its Oilfield Division. Business in the United States increased and, by 1984, the company had 110 owner operators. In 1989, the Company purchased FSJ L.A.N.D. Transport Ltd. and moved the oilfield division to Leduc. A year later, Mullen moved to new, expanded facilities in Aldersyde and implemented its Quality Program.
Over the years, Roland built the company into the largest provider of transportation services to the Canadian petroleum industry, fielding 1100 trucks and 2000 employees and owner-operators.
In 1993, Mullen Trucking became a publicly owned company. Every employee became a shareholder.