Overhead services are more exposed to ice, high winds and flying debris. Underground facilities are subject to flooding. Damage to an overhead transformer is often easier to find. Damage to a pad mounted transformer serving underground cable may not be readily visible. Underground lines are susceptible to damage from digging and trenching equipment. And the cost of installing and maintaining underground conductor over hundreds of miles of sparsely populated rural areas would result in an enormous increase in the cost of electricity to you.