All Korean rural regions fall in the category predominantly rural close to a city (i.e., there are no rural remote regions in Korea). Korea has 22 functional urban areas covering 26% of the national territory. Out of the 22 FUAs, five are classified as large metropolitan areas (with a population of 1 500 000 or more), and six as metropolitan areas (with a population of 500 000 to 1 500 000), eight as medium-sized urban areas (population between 250 000 to 500 000 people) and three as small urban areas (population between 50 000 and 200 000 people). This definition overcomes previous limitations for international comparability linked to administrative boundaries. This methodology is a clear example of how geographic/morphological information from geographic sources and census data can be used together to get a better understanding of how urbanisation develops. These clusters are made of contiguous 1 km2 grid cells with a population density of at least 1 500 inhabitants per km2 and a total population of at least 50 000 people.