A new automated method to retrieve charge layer polarity from flashes, named Chargepol, is presented in this paper. Using the RELAMPAGO field campaign NASA Lightning Mapping Array (LMA) data deployed in Cordoba, Argentina, from November 2018 to April 2019, this method estimates vertical charge layer polarity, altitude, and depth from VHF-based observations of lightning flashes and, when extended for long periods of time, infers charge structure for thunderstorms’ entire life cycle. This method provided reliable charge retrievals as demonstrated in validation when assigning VHF lightning source polarity manually. Examples of Chargepol applied to normal and anomalous charge structure storms in Central Argentina during RELAMPAGO are presented for the first time. Application of the algorithm to months of LMA data in Central Argentina and several locations in the United States allowed for the characterization of the charge structure in these regions and for a reliable comparison using the same methodology. About 13.3% of Cordoba thunderstorms presented an anomalous charge structure, slightly higher than in Oklahoma (12.5%) and West Texas (11.1%), higher than Alabama (7.3%) and considerably lower than in Colorado (82.6%). Some of the Cordoba anomalous thunderstorms presented enhanced low-level positive charge, a feature rarely if ever observed in Colorado thunderstorms.