This map shows how commercial activity is distributed within urban areas and the impact of commercial services on the urban landscape, by mapping what proportion of stores (hence jobs) in an urban area that are found in the downtown. Downtowns are typically the oldest and most central commercial location in the city. Initially, they provided retail and institutional services, but over time much of the retail activity has migrated to the suburbs and the downtown has attracted a variety of other services into office buildings. The importance of the downtown varies widely from city to city. Smaller cities have relatively larger downtowns, as do cities with a strong indices of centrality because they provide services to a wide trade (market) area.