The world is becoming more urban, so what makes the study of rural demography relevant today? In this chapter, we argue that more than population numbers and percentages are involved in understanding rural demography. Local economies, the organization of institutions, and distinctions in norms, values, and lifestyles can result in divergent demographic dynamics and patterns in migration, family formation, and aging across the rural-urban gradient. As a first task, we consider how to best conceptualize rural populations. We then focus on theoretical and substantive issues confronting rural populations in the United States, highlighting compelling demographic research already pursued and identifying several emerging topics that require critical attention by demographers in the years ahead.