Records include 2 personal subgroups: Wellington D. Rankin and Wellington D. Rankin Estate; six family subgroups; a political subgroup; a ranch subgroup; ten business subgroups; a subgroup for Rankin's law practice; and small personal subgroups for two of Rankin's law partners.

Wellington D. Rankin's Personal Subgroup includes correspondence (1913-1966) with a wide range of family, friends, business colleagues, political associates and Christian Science practitioners; minor financial records (1918-1965); minor legal documents (1930-1957); subject files concerning his Missoula properties, a Butte electric franchise, and other topics; miscellany, including greeting cards; and clippings concerning Christian Science and other topics of interest to Rankin.

The Wellington D. Rankin Estate Subgroup contains correspondence re claims on his estate and financial records including a list of stocks he owned at the time of his death.

The Rankin Family Subgroups consist primarily of letters among family members Mary Rankin Bragg, Louise Replogle Rankin Galt, Grace Rankin Kinney, Edna Rankin McKinnon, and Jeannette Rankin. In addition, Jeannette Rankin's papers include printed material she collected on various political and social topics such as the plight of Jews in Europe, women's suffrage, the trade union movement and women in industry. There are also a number of speeches, subject files on her 1940 Congressional campaign, and clippings.

Wellington D. Rankin's Political Files include correspondence with several Republican Party activists including Frank Hayes, Gladys Knowles, and Rita Shields, plus additional correspondence (1922-1962) arranged chronologically. There are also speeches by Rankin, and by others supporting or opposing his political candidacies; subject files on his campaigns for various offices; files on labor, legislation, the Republican Party, silver policy, and other topics.

Rankin's Ranches included the Avalanche, Birch Creek, A.B. Cook, Moss Agate, Stafford-Floweree, Miller Brothers, and "71" ranches. Records include correspondence (1931-1933, 1958-1965) with and about employees and about the purchase of various ranch properties; employment records including payrolls (1938-1959) and employment contracts (1947-1967); financial records; legal documents (1921-1969) consisting primarily of bills of sale for livestock, land, and equipment, including substantial purchases from F. Hervey Cook; subject files on timber harvesting, grazing, and various properties; and miscellany.

There are relatively minor subgroups for some of Rankin's various Business Ventures, including ABC News, the Brazier Brothers Company candy business, the Grand Hotel Company in Billings, the Helena Hotel Company, the Montana Ready-Mix Company cement plant in Missoula, the Pittsburgh Block Company, the Red Rock Producing Company, the Sherman Music Company, the Weiss Café/Mint Bar, and files concerning many of Rankin's mining investments including correspondence and assay reports, and annual reports on several mines.

In terms of quantity, the largest subgroup is Rankin's Law Practice records. Much of this material is restricted due to attorney-client privilege, including client correspondence, and portions of many case files; however, much is open to research. Most of the open correspondence concerns the building of Rankin's law library, the equipping of his office, and routine legal tasks such as the scheduling of cases. Case files are open except for correspondence with clients or opposing attorneys. The case files (predominantly 1911-1925, but also some from the 1940s-1960s) cover the diversity of Rankin's practice and give a picture of his effectiveness as an attorney. In addition to the case files, the law office subgroup includes financial records of the law practice; legal documents, including Rankin's contracts with his clients; a subject file on the Montana Trial Lawyer's Association; and miscellany including jury lists (1926-1933) for Billings, Butte, Great Falls, Helena, Havre, and Missoula.

There are two very small subgroups for personal papers of Rankin's law partners Charles L. Zimmerman and Arthur P. Acher.