In this talk, we present a detailed case study of a variety of dative constructions that vary across speakers of American English. We show how geographical maps of acceptability judgments can be used to shed light on the syntactic structures underlying those judgments. Those structures can then be used to refine our understanding of syntax more generally, in this case relating to the features of argument-introducing heads. We provide novel support for the low applicative analysis of the Personal Dative construction, on the grounds that this analysis falls in line with a general, somewhat surprising conclusion about Southern American English: that ApplP may occur not just as the complement of a verb, but also as the subject of a small clause or the complement of a preposition. We propose that this wider distribution follows from a featural difference between Appl in northern and southern varieties: that low ApplP in Southern American English is not categorially distinct from ordinary DPs. We then show that even though Personal Datives have spread outside of the South, they have not taken this basic structure with them. Instead, northern varieties adopting the Personal Dative have made a minimal modification to their existing Appl heads, to accommodate the canonical Personal Dative without adopting the full range of dative constructions found in the South.