International survey researchers are increasingly turning to a geospatial sampling approach known as gridded population sampling for finer resolution and a more updated sampling frame than conventional census-based sampling. To date, there have been no direct comparisons of accuracy between survey results derived from the two methods. This experiment fielded two parallel public opinion surveys concurrently before Uruguay's 2019 first-round election to compare the accuracy of both probabilistic sampling approaches. Holding other factors constant, we found that the gridded population sample survey performed slightly better than the conventionally drawn census sample survey at predicting election results. The quality of the Uruguayan census frame set a high standard for the gridded population sample, and our experimental results demonstrate that it surpassed it. Given gridded population sampling's additional demonstrated advantages, particularly time savings, these results suggest that it is a promising approach for face-to-face survey sampling in many lower- and middle-income countries.