This article describes the way in which a unique new quantitative data resource and evidence base has been used to relate historic measures of U.K. migration flows to the contemporary socioeconomic patterning of neighborhoods. The resource enables generalized analysis of the regional origins of British and Irish people from their family names, and makes it possible to relate the current regional distribution of names in the United States, Great Britain, and other English-speaking countries to equivalent information from the Great Britain Census of 1881. Illustrative applications may be viewed at http://www.spatial-literacy.org. In this article we develop a number of indices of the historic origins of English and Irish family names, as a prelude to detailed microscale analysis of late twentieth century surname patterns. We illustrate the usefulness of these various indices through case study analysis of Middlesbrough and East Cleveland, an area of the United Kingdom that attracted large numbers of economic migrants during its rapid nineteenth century industrialization. We use our quantitative evidence of the historical distributions of different family names in order to characterize the social mobility of descendants of Scottish, Irish, and Cornish migrants, and to evaluate the practice of ascribing family names to particular localities in historical GIS. The case study thus illustrates the ways in which our data resource may be used to substantiate existing thinking about historic migration and residential structure, as well as to generate and investigate new hypotheses that might guide future work.