The Midwest Agricultural Chemical Association (MACA) was founded in 1958 to unify the efforts of individuals, companies, partnerships and corporations interested in pesticides in Midwest states and who are engaged in the manufacture or formulation and distribution of agricultural pesticides. States include Illinois, Indiana, Iowa, Kansas, Minnesota, Missouri, Nebraska, North Dakota, South Dakota, and Wisconsin. This group also includes suppliers to the industry.

In its 1960 constitution, MACA stated that its purpose was "to procure and disseminate useful knowledge and information pertaining to the scientific development of agriculture; to advise, assist, and cooperate with State and Federal research programs with Legislative and Regulatory bodies and Administrative agencies in procuring progressive legislation and regulation relating to agricultural chemicals; and to promote better understanding, cooperation, and a high standard of ethics among all persons interested in the improvement of agriculture."

There were 70 member companies and over 120 individual members in 1975. Today MACA, which now stands for Mid-America CropLife Association, still exists as a members-only entity whose purpose is to "research public issues relating to crop production and to work together to improve the crop life cycle via health, safety, and public education."

While MACA was originally headquartered in Des Moines, Iowa, their current headquarters are in St. Louis, Missouri.

This collection (1960-1978, n.d.) contains articles of incorporation, constitution, by-laws, correspondence, membership materials, financial records, minutes, agendas, and a variety of reports and articles such as The Truth About Pesticides. Also included are brochures about the organization, giving their purpose statement and the steps necessary to become a member. The collection only contains records from the organization's first twenty years of existence (excluding the first two years, 1958-1959).

Most of the materials in the collection relate to memberships, including the financial records which contain documents related to membership dues and payments from 1964-1975. Membership records primarily consist of lists of members and records of dues, and the financial records are mainly financial statements and travel expenses for conferences and meetings. Also included are lists of members in "good standing" during the eighteen year period that the collection covers. The meeting minutes, from both the annual and board meetings, contain great summaries of the organization's activities and concerns. Often included are reports on short courses and by committees and the states. Minute files often contain lists of officers and directors and the treasurer's reports.