The methodology – preparing genealogical data for maps

The production of the map showing the emigration of Bührers from Switzerland to the United States relied on the following, largely self-developed sequential steps:

  • Normalization, completion and geocoding of places used for family and persons events
  • Identification and categorization of in-scope persons, notably persons born as Bührer or name varieties such as Buehrer (“Named”), spouses (“Married”) and their children/grandchildren (“Descendant”) that have different family names
  • Constructing a sequence of geocoded events for a person’s life, also considering childbirth for women. In case geocoded events lacked dates a natural sequence was assumed, i.e. birth followed by marriage, childbirth, death and burial.
  • Determination of an emigration/residence status relative to Switzerland, the US or third countries. Of particular interest were those that emigrated to the US as well as confirmed or assumed US residents
  • Determination of a common male ancestor for all Bührers that emigrated or have lived in the US and the generation relative to him
  • Deriving a family status for emigrants, i.e. whether emigrants emigrated as single, with their spouse or family
  • Assignment of persons to a time period (generations prior/beyond 1880) based on known birth years, ensuring a consistent assignment of couples and siblings to the same period
  • Construction of migration path segments following the sequence of geocoded events
  • Aggregation of migration paths per county and time period, including aggregated indicators such as the category of in-scope person with Bührer prevailing and the minimal generation involved
Geocoding places in MacFamilyTree
Geocoding places in MacFamilyTree
Sample PostgreSQL script
Sample PostgreSQL script (categorization of in-scope persons)

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