This series contains records relating directly to William McPherson, his life, and activities. The materials may be broadly divided into correspondence, diaries, notebooks, and geographic and subject files.

The bulk of the surviving correspondence derives from McPherson’s love affair with his first cousin once removed, Cora McPherson (born 1905), whose father, Isaac (1861-1936), son of Stephen McPherson’s elder brother, Chiles (1835-1914), had settled in Seattle, Washington, between 1905 and 1910; while the love affair, begun in 1932, was over by 1936, and in late 1938/1939, Cora married another man, the correspondence continued, in an increasingly desultory manner, until 1959. Although McPherson was well known for his generosity in sharing his knowledge of Southern California literature, local history, and anthropology, very little correspondence on these subjects survives in the collection.

McPherson’s diaries, extending from 1898 to 1951, but with only sporadic entries after 1945, chronicle McPherson’s daily life; his involvement in the avocado industry; his research on local history and anthropology; his collecting of books, manuscripts, and historic documents; and his love affairs.

McPherson’s notebooks may be divided into general notebooks and commonplace books, with information on a wide range of personal and research topics entered chronologically; and research notebooks, containing notes, sometimes entered over a period of time, on a specific topic of interest. With a single exception, the research notebooks are numbered; however, it is not known whether these numbers were assigned by McPherson himself, or by Don Meadows during the time these materials were in his custody.

McPherson’s geographic and subject files contain notes, newspaper and periodical clippings, flyers, leaflets, brochures, pamphlets, ephemera, and, upon occasion, correspondence and photographs. The bulk of the materials dates from before 1945, and was collected, created, and received by McPherson in the course of his studies of Southern California history and anthropology, and of his collecting books, manuscripts, and historic documents. Other materials document his interest in politics, and chart his shift from populism to increasingly conservative Republicanism. The geographic files are particularly rich in promotional materials for Southern California counties, in particular, Orange County, for the period from approximately 1910 to the mid-1930s.

Additional materials in the series include a copy of the Congressional Record for 1904-1906 used as a scrapbook for clippings dated circa 1900-1909; McPherson’s school register (including names of students and their grades) for the San Juan Capistrano School District in 1916; and a few miscellaneous business records and ephemera. Records of McPherson's avocado business, and his studies of the Southern California avocado industry, were found comingled with, and could not be effectively disentangled from, the records of the Avocation Association of California and of the California Avocado Growers Exchange/Calavo Growers of California; all these materials have been grouped together to form Series 2.1. Avocado Association.