Series 2A is divided into two parts: chronological (part I) and subject (part II). The chronological section is arranged in strict chronological order by year, and then alphabetically by author or subject within the chronology. This section covers the years 1811 to 1884, with undated items arranged alphabetically at the end. The material in the chronological section is varied but with an emphasis on the business and economic affairs of Cyrus H. McCormick. Included, in either original or copied form, are deeds, partnership agreements, investment proposals, business accounts, contracts, promissory notes, receipts, medical prescriptions, business correspondence from agents, as well as letters relating to religious institutions, politics, the Civil War and personal and family items.

Boxed material in the subject section is arranged alphabetically: from “Advertising” to “YMCA.” Within each subject division, however, folders may be arranged alphabetically or chronologically. Thus the subject division “Mines” is first arranged alphabetically by state, then chronologically within each state. The subject division “Appeals” is first arranged chronologically and then alphabetically within the chronology.

Following the subject boxes are five bound volumes relating to the Dorn Mines, stock transfers and the Mississippi Valley Society.

Material in this series is cataloged on 3x5 cards, contained in four card files. The catalog is set up alphabetically by author or subject. Cards indicate the year to look under if the item is in the chronological section. If the item is filed under a subject heading, the card gives the subject and the year. The bound volumes are not cataloged but are shown in the shelf list for 2A.

The content of each box is listed according to the title of the first and the last folder in the box. In cases where more than one subject is contained in a box, the listings are for the first and last folder of each subject division.