The Hidden Politics of Grammar is a thorough investigation into a corpus of historical American grammar texts, revealing how their linguistic choices decisively contributed to the creation and maintenance of an explicitly American identity. Drawing on a newly compiled corpus of 18th- and 19th-century American grammars of English (HistAGram), this study challenges the perception of these texts as neutral instructional materials. Instead, spelling conventions, lexical choices, and recurring themes of patriotism and shared heritage demonstrate the texts’ political nature because they reflect and replicate their authors’ national beliefs and ideologies. Du Bois employs a mixed methods approach, combining methodologies from historical corpus linguistics, discourse analysis, and network analysis. The research also introduces a comparative dimension through a parallel analysis of the HeidelGram corpus and the Corpus of Historical American English (COHA), exploring how both British and American grammars similarly construct their respective national sentiments. This monograph is essential reading for researchers in corpus linguistics, historical linguistics, sociolinguistics, discourse analysis, and American studies. It will also be of interest to scholars in education history, publishing history, and political discourse studies.