The diachronic change of English relativizers: a case study in the <i>State of the Union</i> addresses across two centuries

Abstract Different types of relativizers are used to introduce relative clauses, and the change in the use of relativizers has attracted attention in recent decades. Despite progress in this area, the challenge of extracting relative clauses, especially those with zero relativizers, has limited our understanding of relativizer change. To this end, we investigated the evolving patterns of relativizers in the State of the Union addresses spanning two centuries, employing novel methodologies developed for this purpose. Different from findings of previous studies, our results showed an increase of that and a decrease of which in subject relative clauses, and an increase of zero relativizers in object relative clauses. The change could be attributed to changes in factors concerning text complexity and styles. The faster change rate around 1940s can be explained by factors such as prescriptivism and the transition in speech styles. Methodologically, our study has confirmed dependency parsing as a reliable method for automatic extraction of relative clauses.