This dissertation examines the urban mystery in relation to the popular press in order to show how genre and form, modes of publication, and representations of urban space, crime, and punishment all contribute to the formation of national identity in nineteenth-century France and Quebec. Specifically, it explores the ways Eugène Sue’s genre-launching serial novel, Les Mystères de Paris (1842–1843), uses literature and the press to make significant interventions in socio-political debates on social and penal reforms, not just reflecting public opinion, but actually forming it. In the following chapters, I analyze Sue’s novel as well as the works of Sue’s Canadian imitators, who each produced a novel bearing the title Les Mystères de Montréal. These three novels mark three distinct phases in the evolution of not only French-Canadian literature, but also French-Canadian national identity. Chapter Two argues that Henri-Émile Chevalier’s serialized Mystères de Montréal (1855), along with his journalism, make a landmark contribution to the inauguration of French-Canadian literature. Chapter Three proposes a reading of comedy and urban space in Hector Berthelot’s serio-comical Mystères de Montréal (1879–1881). It argues that by using (auto)parody in representations of both French Canadians and a newly industrializing Montreal, Berthelot is able to subvert Church censorship, enlarging the public sphere, in order to facilitate the reader’s affirmation of French-Canadian identity. The final chapter relates Auguste Fortier’s Mystères (1893) to Chevalier’s prescriptions the inauguration of a specifically Canadian national literature in French, as well as to his development and affirmation of his predecessors’ visions for French-Canadian national identity, in a thoroughly cosmopolitan Montreal. Ultimately, my analysis of these works’ participation in a global cultural imaginary demonstrates the ways the blurred boundaries between literature and the press facilitate the circulations, transfers, and appropriations of both texts and ideas across very permeable national, political, and social boundaries. Straddling literary, cultural, and urban studies, this transnational study provides a panorama of these four popular novels, considered together in light of their capacity to reflect and form not only public opinion, but also national identity.