The largest series in the collection, it contains personal family letters and is housed in twelve archival boxes. Correspondence between Berkey and the authors, including his wife Minnie, his daughter Virginia, his son Paul, and his grandchildren is organized together chronologically, as are additional letters between several of these relations. The correspondence generally covers topics such as Berkey's travels, health, and other family matters. Paul Berkey described his experiences in the military to his father in some correspondence, while other letters bring their intended recipients up to date on such events as weddings and birthdays.

This series contains printed biographical information, autobiographical manuscripts, letters of personal commendation, and birthday correspondence. In 1937, on Berkey's 70th birthday, a surprise dinner was held in his honor. Over 300 guests attended it from several countries. This series contains a large number of letters from those who were unable to attend, as well as the invitation, program, and speech transcripts. This series also has the printed obituaries and official memorials dedicated to Berkey. His daughter, Virginia Berkey Hartigan, presumably collected this last part.

This series contains only a very small portion of Berkey's published works and unpublished manuscripts. There is a listing of his extensive publications in the first folder of the series. Berkey was invited to give a series of lectures for Columbia University in 1914 - 1915 called the Jessup Lectures. Drafts and completed copies of these lectures are contained in this series.

Berkey maintained a long-standing relationship with his mentor at Columbia University, James Furman Kemp. Their correspondence deals with both professional and personal matters but is kept in this one series for ease of organization. The large amount of miscellaneous correspondence contains letters and telegrams from Berkey's employers and colleagues. This series maintains Berkey's original classification order.

This series consists primarily of newspaper clippings from Berkey's many projects throughout the United States. Also contained in this series is the extensive record of Berkey's trip to Mongolia in 1925. The expedition was followed closely by the United States press and Berkey gave lectures and interviews on this event for many years.

Berkey was the recipient of numerous awards, medals, and honorary degrees. This series contains newspaper announcements, congratulatory correspondence, and official invitations and programs of the ceremonies. It is organized according to the date of the award.

This series contains the mundane official documentation of Berkey's professional career. It contains his handwritten (and undated for the most part) itineraries that he left for his family, as well as legal documents. The contracts, licenses, and invoices necessary for a professional career are contained in this series. The last folder in this series contains two of Berkey's geological journals in which he kept notes of the projects for which he consulted from 1945 - 1948. They contain minutes of meetings, random observations, and topographical sketches.

This small series contains clippings and official letters that pertain to Berkey's wife, children, and grandchildren. Minnie Berkey, the wife of Charles, left a sizable donation to the New Jersey College for Women (now a part of Rutgers University) in her will. This series has the correspondence between the College and Charles on the disposition of the funds. The last two folders of this series are long manuscripts in the form of family letters. Charles and Minnie traveled through Europe in 1929 and maintained a running diary complete with photographs. One manuscript treats the journey as a whole, while the other focuses on a tour of World War I battlefields of northern France. Their son, Paul, fought in the war as an artillery officer and the parents traced the movements of his company through his wartime letters.

Berkey toiled on the genealogy of the Berkey Family all his life. This series contains folders of various branches of the family and correspondence between Berkey and distant relatives. The largest amount of information describes the Studebaker-Stutsman line, of which Berkey's mother was a part. The Studebaker family maintained correspondence with Berkey's daughter, Virginia, after his death in 1955. This series maintains Berkey's original classification scheme.

This series is split into three sections: Berkey, professional, and family. All photos that depict Berket are in the first section, while those that only treat the projects on which he worked are in the second. The family section contains several photos of unknown personages assumed to be related to Berkey.

This series contains only two items. The first is an original invitation to the coronation of Edward VII of England in 1903. It is unknown, and considered unlikely, that Berkey attended the coronation. The invitation is unaddressed. The second item is an unsigned engraving of an unknown building, possibly on Columbia's campus.