Some Americans need hyphens in their names, because only part of them has come over; but when the whole man has come over, heart and thought and all, the hyphen drops of its own weight out of his name.

Wilson is criticizing “hyphenated American” identities—labels like “German-American” or “Irish-American”—as signs of divided loyalty. The metaphor suggests that a hyphen marks an incomplete transfer of allegiance: only “part” of a person has “come over,” while “heart and thought” remain oriented toward an ancestral nation. In Wilson’s view, full civic belonging requires an undivided commitment to the United States, after which the hyphen “drops” naturally. The line reflects early-20th-century assimilationist nationalism, especially intense during World War I, and it illuminates how ideals of unity were often framed as demands for cultural and political conformity.