Earthworms are everywhere in the United States, so it’s natural to assume that they have always been there, as much a part of America as the soil in which they live. According to journalist Charles Mann, however, this is not the case. In both his new book 1493 and in an interview on NPR with Terry Gross, Mann claims, in accordance with what other experts have said, that earthworms in the United States are descended from earthworms in Europe, and that American earthworms only exist because Europeans (like Christopher Columbus) brought them over with them. The reintroduction of earthworms into the United States is part of what is now called the “Columbian Exchange.” Why weren’t there earthworms in the United States to begin with? How did Europeans bring earthworms to the United States? Is the introduction of earthworms into the United States characteristic of larger historical forces? Each of these questions will be addressed in turn.