Andrus was born in 1956 in Oak Ridge, Tennessee, to Mary Frances and Francis Andrus and was raised in Kingston, Tennessee. He received his Bachelor of Science in Plant Science from the University of Tennessee, Knoxville in 1979 and a master's degree in social sciences from Virginia Polytechnic Institute and State University, Blacksburg in 1982. After receiving his master's degree, Andrus went to work as a regional planner for the Accomack-Northampton Planning District Commission on Virginia's Delmarva Peninsula.
