Summing viewsheds for several turbines results in a cumulative viewshed representing the number of turbines that can be seen from locations in a study area. Viewshed methods for use in a VIA has changed little since its development in the 1970s. It is an expected component of wind energy VIAs, but how it is used and understood has not been previously reviewed. This paper reviews the use of cumulative viewsheds in VIAs prepared by 25 firms. It then shares the results from an exercise completed by 29 professionals in a GIS workshop to ascertain their understanding of a cumulative viewshed map. Ways are suggested to improve how we conduct and communicate the GIS-based analysis in VIAs.