The large majority of Spanish-speakers today, perhaps 300 million of them, are to be found in the Americas, in a vast area which stretches from the southwestern United States to the far south of the southern continent, not to mention the large cohorts of Hispanophones to be found in major US cities such as New York. We find, as we expect, geographical variation across this area, although mutual intelligibility among varieties is rarely threatened, and certainly not among educated and urban speakers.

Until recently, detailed linguistic studies of American Spanish have most usually been focused on the language of individual countries, and the linguistic atlases so far published continue to be oriented in this way (see ALEC 1981–3, ALESuCh 1973, ALM 1990–4, Navarro Tomás 1974). Even excellent surveys of the language of the whole of Spanish America, such as John Lipski's (1994) or the collaborative work edited by Manuel Alvar (1996b), are, at least in part, internally organized on a country-by-country basis. The frequent implication (although disavowed in the best studies) is therefore that the features described have boundaries which are co-terminous with those of the country concerned. This is not so; in accordance with normal distribution, each feature observed in Spanish America occupies its own area, which rarely if ever coincides with the area of any other feature, let alone with political boundaries. That is to say that we are dealing here, as in northern Spain and many other parts of the world, with a dialect continuum which is intersected by the frontiers which separate one republic from another.