Approximately 50 infants/year were born with TOF in NC. One cluster was identified. Further study is necessary to explore potential explanations for the observed case cluster. As interest in regionalization of congenital heart surgery grows, GIS and spatial analysis can become increasingly useful tools for health care planning. Birth Defects Research (Part A) 106:881-887, 2016. © 2016 Wiley Periodicals, Inc.