Mr. Stevenson is described as 5 feet 11 inches tall and 250 pounds, with short brown hair, blue eyes and a goatee.
His wife is said to be 5 feet 7 inches tall and 130 pounds, with long brown hair, and blue eyes.
Their children range in age from 1 to 15 years.
One of their vehicles is described as a red and black 1989 GMC pickup, pulling a full size white with blue trim GMC van, both with Michigan licence plates.
The second vehicle, with Louisiana plates, is a large black school bus, with a white roof, and it is reportedly pulling a plywood trailer, which also has Michigan plates.
The family was expected to arrive at its Alaskan destination last Tuesday, and is requested to contact the local police agency in their current travel area, and their family in Michigan.
In addition, anyone else with possible search assistance information is asked to call the nearest RCMP detachment, and in this area the number is 250-784-3700.