A settlement's population size, its geographic area, its status,[clarification needed] and the availability of services can all affect this hierarchy.
In some parts of the United States, the distinction between town and city is a matter of a decision by local government to incorporate.
Status can derive from being the residence of a King or high-ranking member of the nobility or from being the location of a major religious establishment.
For example, a Saxon royal estate might be supported by settlements specialising in the production of cheese or barley or maintaining flocks of sheep.
High income jobs and non-essential luxury services are abundant (e.g. car dealerships, brain surgery centers, airports, financing, computer stores, coffee shops, etc.)
During the Second Industrial Revolution, London, England reached the mark in 1810 and New York City, United States made it in 1875.
At this density, there is ready access to less specialized services but residents may need to travel to a larger city in some circumstances.
Density may be sufficient to support local commercial areas which may include a "Main Street" or a shopping mall.
The term is used a number of times in the guidance for preparing evidence for planning decisions; a settlement hierarchy starts with an isolated dwelling, then hamlet, then village, town, city then a conurbation.
The German planning system is based on the Central Place Theory developed by Walter Christaller in the 1930s and first applied in the Nazi Era, especially in Poland.
These are political plans to achieve goals such as equivalent living standards (Gleichwertige Lebensverhältnisse [de]) in rural and urban areas in all of Germany, east and west.