This is a qualitative analysis of the historical dimensions of Spanish-English and Spanish-Portuguese contact in the Americas, based on 19th century documents from southern California and northern Uruguay. Language mixing is found in both areas, but whereas in California it is limited to the earliest periods and to informal registers, in Uruguay it is long-lasting and pervades all social and stylistic levels. Additionally, there are differences in the linguistic scope of mixing in both borders. In California it manifests itself through borrowings and syntactic and semantic calques, whereas in Uruguayan documents switching within constituents is frequent and pervasive. Finally, writers in California exhibit metalinguistic awareness of language contact, whereas no such awareness is evinced by Uruguayan authors. Commonalities are attributable to universal outcomes of contact and to historical and social parallelisms, while differences are due to linguistic family resemblance and to more balanced prestige and demographics in northern Uruguay.