This paper deals with three problems encountered in the areal study of "colonial" and "immigrant" languages (used in Haugen's sense) and examines how data presented in tabular or map form can assist in their solution. They are: (1) the mechanisms by which the speakers of various dialects of a single language--dialects which were often mutually unintelligible in Europe--make themselves understood in the new situation; (2) the compilation of glossaries recording the lexical "adjustments" brought about by a socio-physical environment ranging from somewhat different to much different from that of Europe; and (3) idiolectal versus communal effects of wholesale bilingualism over large areas. The author maintains that a process similar to the creolization of a pidgin or contact language takes place in interdialectal situations involving the immigrant generation as opposed to succeeding generations. He discusses the use of theory oriented (rather than data oriented) elicitation procedures and questionnaires for both phonology and syntax in the light of recent theories of rule reordering and rule additions in areal linguistics. (Author/DO)