Resumen: Water management and population issues have always been particularly important in Spain, a country historically characterized by severe environmental constraints on agricultural growth and intense rural depopulation. This paper evaluates whether irrigation projects in Spain over the course of the twentieth century have achieved one of their main objectives, which was to reduce rural population decline. This paper makes two contributions. First, we compare the evolution of population in two of the earliest and most ambitious irrigation projects in Spain, the Riegos del Alto Aragón (Upper Aragon Irrigation System) and the Canal de Aragón y Cataluña (Aragon and Catalonia Canal System), both located in the Ebro basin. Second, the time period of the study spans an entire century. This long-term approach is crucial if we accept that irrigation requires time to consolidate its effects and, therefore, its impact on population may be long delayed. We show that the evolution of population in each of the two projects has been substantially different. We also analyze the factors that have caused or prevented population growth. We argue that financial, economic and environmental limitations have been significant, but also that political and geographical factors have played a major role. Idioma: Inglés DOI: 10.1016/j.jhg.2009.10.004 Año: 2010 Publicado en: JOURNAL OF HISTORICAL GEOGRAPHY 36, 3 (2010), 315-326 ISSN: 0305-7488 Factor impacto JCR: 0.983 (2010) Categ. JCR: HISTORY OF SOCIAL SCIENCES rank: 3 / 26 = 0.115 (2010) - Q1 - T1 Categ. JCR: GEOGRAPHY rank: 37 / 66 = 0.561 (2010) - Q3 - T2 Tipo y forma: Artículo (PostPrint) Área (Departamento): Área Hª e Instituc.Económ. (Dpto. Estruc.Hª Econ.y Eco.Pb.)