Early on a misty winter morning, Corinne Konecny, 39, takes the elevator to the microfilm-research room on the fourth floor of the National Archives and Records Administration in Washington. She is looking for her great-great-grandfather, whose name was Solomon Seif.
A cousin who just located Solomon Seif's burial place in Galion, Ohio, noticed on the gravestone that he had been a Civil War soldier. Konecny made note of that on a scrap of yellow legal-pad paper, and now she is spending a day at the Archives. She has been working on her German and French-Canadian family tree for 10 years, determined...