This book is the genealogical history of the ancestry of Jacob (Stephen) Gruben and Maria Emilie Krmer who came to the United States from Germany in the early 1880's. The book traces each of their ancestries back through German civil registration records and the earlier Catholic Church records to the 17th century. The book includes information about the first generation born in the United States. Similarly the book traces the family of Johann Gottfried (Godfrey) Nienhaus, a nephew of Jacob (Stephen) Gruben, who also came to the United States at about the same time. The book contains information on the first generation of the Nienhaus family that was born in the United States.

The book is of wider interest because there is a discussion of the nature of and idiosyncrasies of the German civil registration and Catholic records available in the Dsseldorf / Cologne area of Germany. There is an extensive discussion of a method of determining a family line when faced with the sometimes scant information available in the early Catholic Church records.

There are large numbers of collateral relatives listed in the lines of descendants contained in the book with over 1800 people listed, most of whom were born, lived and died in the Dsseldorf / Cologne area of Germany. There is a surname index to the lines of descendants in the Gruben section and a surname index to the lines of descendants in the Krmer section of the book.