The Biographical series contains biographical sketches, clippings, awards, correspondence between Kemmerer and family members, especially his son Donald Kemmerer, and photographs. The series also includes a guestbook listing the visitors to the Kemmerer home from 1920 to 1941 and a small amount of material related to Princeton University and Scranton-Keystone Junior College.

The Country Files series documents Kemmerer's financial advisory work and also contains materials collected by Kemmerer as he conducted research on particular countries. The series contains material from twenty-six countries, mostly in Latin America. The best documented are China, Colombia, and Peru, and to a lesser extent Chile, Ecuador, the Philippines, and Poland. The papers include correspondence, reports, clippings, and government publications regarding a wide variety of subjects, including banks and banking systems, currency and monetary policy, government budgets and debt, taxes, trade laws, and information regarding the economic and social conditions of the countries. The papers also include correspondence, reports, clippings, and other materials of the commissions of financial advisors lead by Kemmerer.

Series 6 is largely composed of materials related to Kemmerer's work as a financial advisor leading international financial commissions. The materials include bound copies of reports submitted to the governments with the commissions' recommendations and photograph albums and scrapbooks of clippings that document the time spent by the commissions in the countries, as well as a small number of books. Supplemantary materials that were kept in rolls may be found in Series 7.

This series includes the Bradley Senate office's administrative records. Most records in this group were created by Marcia Aronoff, Marina Gentilini, and Margaret Hawthorne, and consist of schedules, invoices and receipts, and routine correspondence.

The Biographical series is composed of photographs and memorabilia mounted on pages in approximately chronological order. The pages document Widenmann's travels, attendance at conferences, and informal interactions with colleagues and friends, and also include a smaller amount of material on Loeb, Rhoades Company and United States financial conditions. The photographs include formal group photographs, head shots and candid shots of event attendees at receptions, images of tourist attractions, and images of individuals at parties and on the beach. Some photographs include captions with the names of the individuals in the images. The memorabilia include clippings of articles and political cartoons, event programs, travel itineraries, invitations to events, Widenmann's name tags, and travel brochures. In addition, there are three bound volumes with similar content.

The Correspondence series contains Widenmann's professional correspondence with bankers, businessmen, government officials, and academics. The majority of the letters are in response to Widenmann's requests for copies of articles or speeches, often with the requested item and sometimes with Widenmann's comments on the item. The series also includes correspondence between Widenmann and United States government officials regarding his views of financial policies, Widenmann writing colleagues about the state of the stock market and United States financial conditions more generally, correspondence in relation to his involvement with professional organizations and conferences, and invitations to events.

The Topical Files series contains copies of articles, speeches, testimonies before Congress, press releases, memoranda, and publications collected by Widenmann on a variety of subjects. The subjects include monetary, financial, and economic conditions in the United States and internationally, United States government financial and economic policies, gold, the stock market, business, and reports on the performance of individual businesses. The materials were produced by banks and businesses, professional organizations, scholars, and businessmen.

The Writings series includes Widenmann's writings for use within Loeb, Rhoades Company and drafts of articles and speeches presented to the financial, economic, and business communities. The subjects of his writings include monetary problems, gold and the gold standard, the United States economy, and the money and stock markets. The reports for Loeb, Rhoades Company include analysis of these same subjects, as well as discussions about the performance and strategies of the company. The series also includes a few reports written while Widenmann was an executive at Ludwig Bendix's firm, and a few of Widenmann's student papers.

The Research Files series contains notes, drafts, and correspondence related to Ryder's various projects. Additionally, some folders contain finished publications.