Population and Settlement geography focuses on population clusters, why they arose, and what sustains them. Settlement geography is archaeology’s younger sibling. As archaeologists unearthed ancient civilizations, three settlement patterns emerged: dispersed, linear and nuclear. Dispersed settlements had no central point. It is the study of the ways in which spatial variations in the distribution, composition, migration, and growth of populations are related to the nature of places. Linear settlements clustered along rivers, creeks and streams, and later along migration routes, railroads and highways. Nuclear settlements occurred along crossroads, at river mouths, adjacent to bays, and near centers of industry.