What do we mean when we say “the nineteenth century”? Where does it begin? Where does it end? What does it contain or exclude? How do we make such choices—on what basis? Surveying four major textbooks, this review offers a look back at the ways these questions have been answered over the past two decades, beginning with the first publication of Robert Rosenblum and H.W. Janson’s 19th-Century Art in 1984 and ending with the second edition of Petra ten-Doesschate Chu’s Nineteenth-Century European Art in 2006.[1] Although other forms of scholarship (journal articles, monographs, exhibition catalogues, and the like) perform such work, the textbook’s overt task is to define the field. The textbook, that is, exercises a disciplinary mechanism, self-consciously engaged in the project of canon-building, perpetuation, revision, or reform.[2] The problem of definition is particularly thorny in the case of these four textbooks, since the enduring centrality of the concept of the “long nineteenth century” shapes the ways we study and teach the period. According to this trope, the nineteenth century begins and ends with two equally bloody, paradigm-shifting events, thereby stretching from the political revolutions of the late eighteenth century in France and America to the battlefields of World...