Die Zahlen für die USA stammen von der Webseite des US Census Bureau bzw. wurden mit dieser abgeglichen.
Für die USA gibt die Quelle folgendes an: "Data are as of April 1. Urban and rural population for the United States are counted in census years. The urban population comprises all persons living in places with 2,500 or more inhabitants incorporated as cities, villages, boroughs, towns, and in certain other census-designated urban areas. The population not classified as urban constitutes the rural population."

Für die UdSSR gibt die Quelle folgendes an: "Census data. The classification of the population into urban and rural components is based on the administrative status of the place of residence, not on the population size. The administrative status reflects the basic form of activity of the employed population of that place of residence (either agricultural-rural or lndustrlal-urban). Urban areas include cities, urban-type settlements, workers' settlements, and health-resort settlements. All remaining populated places are considered to be rural areas."