The main article for this category is Families of Nassau County, New York. Please create and/or use it for appropriate text and to list qualifying people, places, sources, etc that may not yet have their own pages.
When this category grows, it may have subcategories for:
families who lived in the county in a specific period
Article and subcategory pages for a specific surname, such as "McXyz families of Nassau County, New York", should be categorised not only here but also in the corresponding "surname in place" category, such as "Category:McXyz in Nassau County, New York". Contributors should consider using the simpler name (e.g. "McXyz in", rather than "McXyz families of") so as to include all the families and apparently isolated individuals of that name rather than separating them.