During the 1960s, Seaholm received a grant from the New Horizon program to write a history about Swedish immigration to Canada. Although he never finished writing a book about this topic, this collection contains much of his research related to this ambition. The collection consists of correspondence, reports, minute books, newspaper and magazine issues and clippings, periodicals, books pertaining to Sweden and/or Swedish immigrant history, and research material about Swedish activities in North America. The series also contains a photograph collection of the Swedish community in British Columbia.

The series contains eight subseries: General research material; Photo collection; "They left something behind" collection; Book Collection; Swedish Pioneer Historical Quarterly periodicals; The Bridge (Brggyan in Swedish); Swedish Press Publishing Company; and Newspaper clippings and miscellaneous articles.