This part introduction presents an overview of the key concepts discussed in the subsequent chapters. The part provides guidance for how these datasets can be used to facilitate studies of residential patterning and segregation across urban America. It presents the importance of geocoding individual level data and combines the population data with urban environmental data to present three case studies. The three case studies are the deportation of Jews from Paris during WWI, the transformation of Paris from an industrial to post-industrial city though following the growth of green space, and the use of geo-referenced aerial photography to discover urban change. The part analyses the German immigration and settlement patterns in New York's Lower East Side. It utilizes the historical fire insurance plans and individual-level census and city directory data to geocode London Ontario's entire population to their individual residence and outline a detailed procedure for record linking individuals across the decade 1881–1891.