Trust in maps is essential for the use of maps, but the factors that lead to a more or less trusted map have been understudied and are poorly understood. To understand the problem space of trust in maps, a framework previously used for understanding visualization trust has been adapted specifically for maps and a comprehensive review of 32 relevant map and visualization trust papers was undertaken to identify design choices which have been theorized to effect trust and to conceptualize the current understanding and research gaps in map trust. Within this framework, we identify the most likely antecedents to lead to the creation of trust, while also acknowledging the existence of a behavioural dimension and the role of heuristics in processing and trusting a map, both ongoing questions about the construction of trust in maps. We also outline future research opportunities to make true strides in understanding how design choices affect trust in maps. This paper stands as a foundational stone on the road to understanding trust in maps and developing practical guidelines for cartographers to design with trust in mind.