On December 1, 1945, a group representing the Swedish‑American communities of Chicago, Rock Island, Minneapolis‑St. Paul, Rockford, and New York City met at the Swedish Club in Chicago to discuss plans for a 1948 centenary celebration of the settlement of Swedish pioneers in the Midwest. The suggestion for this celebration had been made that autumn by Naboth Hedin of New York.
One impetus for a 1948 date was the one hundredth anniversary of the Augustana Lutheran Church, which was being celebrated that year, particularly in Rock Island. It was decided by the group that instead of having one large event for the entire area, it would be wisest to encourage the celebration in many local areas. Invitations were extended to the Swedish government and to the governors of Illinois, Michigan, Wisconsin, Minnesota, Iowa, Nebraska, and Kansas to establish commissions and help organize various events.
In June of 1947, the Board of the Association appointed Professor Nils William Olsson of the University of Chicago to be Executive Director. That summer, local chapters in Chicago, Rockford, Detroit, and Rock Island were organized. Later committees were organized in the Twin Cities, Omaha, Lincoln, Des Moines, Milwaukee, Princeton, IL, and Lindsborg, KS. New York and Philadelphia were also to take part.
The centennial celebration took place during the month of June 1948, starting with a program at the Chicago Stadium on June 4th, where approximately 18,000 people gathered to hear President Truman, Prince Bertil of Sweden, Carl Sandburg and others speak and perform. Prince Bertil took part in many of the celebrations throughout the Midwest and New York State.
In addition to the various programs organized for the centennial, commemorative stamps were issued in both Sweden and America. At the conclusion of the centennial, it was decided to convert the Association into an historical society. On October 15, 1948, it was officially incorporated as such. In March, 1949 all Association interests were transferred toward its reorganization as an historical society, and in early 1950 the Association changed its name to the Swedish Pioneer Historical Society.