© Springer International Publishing Switzerland 2015. America was colonized by Asian migrants who moved from northeastern Siberia into North America, either coastally or by an interior route through now-submerged Beringia, and from there spread southward eventually to settle in the entire hemisphere. Linguistic evidence can shed light on when colonization began; whether it was initially coastal, interior, or both; how many distinct populations were involved; and how rapidly the hemisphere was colonized. The time required to generate the historically attested number of languages and language families in the Americas can be estimated; frequencies of structural properties in areally defined linguistic populations can discriminate between populations and point to geographic origins; and attested and straightforwardly reconstructable rates of language spread can be used to estimate rates of migration and demographic spread. On the linguistic evidence, colonization must have begun before the Last Glacial Maximum. There were at least two distinct populations, perhaps corresponding to interior and coastal immigration routes, and in general, coastal immigration seems to have had a stronger and more varied impact on the linguistic population of the Americas than interior immigration did. The immigrants spread at not much over 1 km/year on average (depending on ecology), taking about 7,000 years to reach southern South America. The linguistic dates are robust and based on plentiful and carefully analyzed material, so they cannot be dismissed, although they conflict with the younger ages estimated in genetic, archaeological, and paleoclimatological work.