Found this in wikipedia. It claims they were worn by surveyors or "engineers". Hope it helps
Similar to harness boots, engineer boots are a type of motorcycle boot: footwear usually worn by motorcycle riders. The boots are most often made of heavy weight black leather, have a rounded toe and range in height from short (10") to extra high (38"). The most typical height is between 10 and 18 inches.
Engineer boots are designed to protect the motorcycle rider from injury to the foot and leg in the case of an accident while riding and to prevent burns of the rider's calves from the heat of the motorcycle parts while riding. They may include a built-in steel toe cap and metal shank in the sole, and often are double layered with leather for stiffness. Engineer boots typically have an adjustable leather strap across the ankle as well as an adjustable leather strap at the top of the shaft to adjust the fit. Multiple straps at the top of the shaft are also not uncommon. Soles and heels are usually made of hard rubber and may either be relatively flat or may have lugs for increased traction.
During the depression era, Chippewa Shoe Company, of Chippewa Falls, Wisconsin, developed a pair of boots with stovepipe leg and was fashioned over "English Riding Boot" last. In the 1960s, Sears carried the Sears branded Chippewa Engineers and showed them as worn by land surveyors, a possibility as of how the name came about. Another major manufacturer of Engineer Boots is West Coast Shoe Company based in Portland, Oregon. They began manufacturing the engineer boot in 1939. A large portion of their sales began with the shipbuilders in Portland, Oregon, building ships for World War II.