This historical monograph examines the city of Saint-Étienne and its surrounding agglomeration during the nineteenth century, a period marked by rapid industrialization and socioeconomic transformation. Drawing on archival research, the author analyzes the interplay between urban development, economic structures, and social change in one of France’s key industrial centers. The study provides detailed insights into demographic shifts, labor conditions, and the evolution of local institutions amid the broader context of the Industrial Revolution. As part of the IERP (Institut d’Études Régionales et Patrimoniales) series, it contributes to regional historiography with a focus on how industrial growth reshaped both the physical landscape and communal life in the Loire department.