The Minnesota Ethnic History Project (MEHP) records consist of correspondence, reports, research notes, statistical data, chapter drafts, and other related material documenting the process of researching, writing, and editing the book They Chose Minnesota: A Survey of the State's Ethnic Groups. Records are arranged in two major series: administrative records documenting the organization, coordination, and funding of the project, and research records consisting of the actual data gathered in the process of writing the book.

The administrative records, while only a small portion of the collection, provide a fairly comprehensive picture of the project as it developed from its initial discussion stage into one of the Minnesota Historical Society's most prominent and ambitious publishing ventures. Materials include correspondence, memoranda, grant proposals, contracts, reports, critiques of chapters, clippings, and other related papers. Two files contain correspondence and memoranda from and concerning Carlton C. Qualey. Materials in these files are particularly notable as they illustrate the evolution of the project, describing it as Qualey first conceived it in a memo to then Director of MHS, Russell Fridley, and including many subsequent plans and schemes for its content and organization as research progressed. The materials in these files also describe the early attempts at securing grants to fund the study and provide some interesting insights into the relationship between Qualey and his colleagues at the Society. A group of five folders contain records kept by June Drenning Holmquist and Deborah L. (Stultz) Miller, including a great deal of correspondence with researchers and chapter authors concerning the writing and editing process, as well as guidelines on chapter organization and content drawn up for distribution to the writers. There are also comments and notes on many chapters provided by scholars who were asked by the editors to critique the work of the writers. Other materials in the series include contracts and other employment and administrative paperwork, as well as a very useful series of monthly reports. While these reports only exist from 1979 to 1980, they provide a helpful overview of the project during that period just before publication of the book.

Comprising, by far, the bulk of the collection, the research records include census and other statistical data, indexes to ethnic information in various sources, copies of relevant papers and articles, newspaper clippings, research notes, chapter drafts, and other miscellaneous materials gathered and created by the various researchers and writers involved in the project. The first part of the series contains initial drafts written by Qualey and reflecting an early, geographical and topical organizational scheme, which was later discarded for a group by group organization. A collection of materials grouped under the rubric "background files: indexes and raw data," is a valuable starting point for further research, as it includes detailed indexes to information on ethnic groups found in complex sources available at MHS, such as the Northern Pacific and Great Northern railway records and the large collection of county histories. The indexes give the page numbers or other location where data on each ethnic group researched for the MEHP may be found in these sources and, as they were created without the aid of modern computer technology, represent a significant portion of the staff time funded in the first phase of the project. A great deal of time during the first two years of the project was also devoted to extracting and compiling data from the censuses to reveal the ethnic composition of the state over the years. This data, which was later used to create the maps and charts in the book, is included in raw form in the collection. Although initial plans called for computer analysis of the statistical data gathered from the census and other sources, the data was instead compiled manually for the most part. As the preface of They Chose Minnesota points out, this systematic transcription from the manuscript censuses resulted in figures that were often quite different from the published statistics. Summary charts showing the numbers of immigrants from various countries (and migrants from other parts of the U.S.) residing in each county during the years 1850 to 1970 are found in a separate oversize folder (These charts are also available on microfilm) along with color population maps created from the charts.

The balance of the collection consists of topically arranged research files organized in three major groups: materials on ethnic groups, church- and religion-related files, and a set of miscellaneous, alphabetically arranged topical files. The church- and religion-related files, compiled by researcher Susan Diebold, include her essays on fifteen different Christian denominations in Minnesota, along with separate files of research notes and articles on most of them. The files also include an index to the Society's collection of WPA church surveys, which provides a township by township listing of all churches surveyed, with a cross-index by denomination and language.

Unquestionably a highlight, as well as the largest portion of this collection, the series of research files on each ethnic group defined and chronicled in They Chose Minnesota are arranged in roughly alphabetical order by ethnic group name. This organization reflects the chapter organization of the book, which grouped certain ethnic groups together. For example, Russians and Ukrainians are under "East Slavs" rather than after the Romanians, as would be the case if they were filed strictly alphabetically. Also, the Asian groups (with the exception of the Japanese) are organized as a separate group at the end. The files include statistical information, articles, newspaper clippings, newsletters, research notes (sometimes on individual notecards), chapter drafts, and other related material compiled by the researchers and writers for that ethnic group. The Asian materials, in particular, contain a large number of interview notes based on oral histories, some of which are available on audio tape as well (see note on related materials). Note that these interview notes were organized within this collection primarily by geographic location (residence) of the interviewee rather than by name. While project administrators made an effort to retain as much of the raw data and other research material as possible, documentation in the administrative records suggests that in some cases supporting materials were owned and retained by the persons contracted to write the individual chapters.