In geographic terms, a situation or site refers to the location of a place based on its relation to other places, such as San Francisco's situation being a port of entry on the Pacific coast, adjacent to California's productive agricultural lands.
Situations are typically defined by the physical elements of a location that helped determine it as good for settlement, which can include factors such as availability of building materials and water supply, the quality of soil, the climate of the region, and opportunities for shelters and defense - for this reason, many coastal cities are formed due to their proximity to both rich agricultural land and trade ports.
Of the many factors that help determine if a location is appropriate for settling, each can be divided into one of four generally accepted categories: climatic, economic, physical and traditional.
Climatic, Economic, Physical, and Traditional Factors
In order to better categorize which factors ultimately affect settlement, geographers have generally accepted four umbrella terms to describe these elements: climatic, economic, physical, and traditional.
Climatic factors such as wet or dry situations, availability and the need for shelter and drainage, and the necessity for warmer or cooler garb can all determine whether or not the situation is appropriate for settlement. Similarly, physical factors like shelter and drainage, as well as soil quality, water supply, ports, and resources, can affect whether or not a location is suitable for building a city.
Economic factors such as nearby markets for trade, ports for importing and exporting goods, number of available resources to account for Gross Domestic Product, and commercial routeways also play a large role in this decision, as do traditional factors such as defenses, hills, and local relief for new establishments in the location's region.
Throughout history, settlers have had to establish a variety of different ideal factors to determine the best course of action for establishing new settlements, which have changed drastically over time. Whereas most settlements in medieval times were established based on an availability of fresh water and good defenses, there are many more factors that now determine how well a settlement would do given its location.
Now, climatic factors and traditional factors play a much larger role in establishing new cities and towns because physical and economic factors are typically worked out based on international or domestic relationships and controls - though elements of these such as availability of resources and proximity to trade ports do still play a major role in the establishment process.