Spatial diffusion is the process by which an idea or innovation is transmitted between individuals and groups across space. It enables dispersion of concepts or things from a central point of origin to other locations that may or may not be directly connected. There are two main types of spatial diffusion: relocation diffusion and expansion diffusion.
Relocation diffusion occurs when people migrate from one place to another, thereby transferring an idea or innovation to a new location. A good example is the European migration to the Americas, which resulted in the spread of many aspects of the European culture, according to UC Santa Barbara.
Expansion diffusion, on the other hand, is the spread of an idea or innovation through a fixed, non-migrating population. It is subdivided into two main subtypes: contagious diffusion and hierarchical diffusion. Contagious diffusion refers to the dissemination of an idea or innovation from one individual to neighbors or other adjacent individuals. It resembles the spread of a contagious disease. UC Santa Barbara cites the spread of the metric system throughout the world as a prime example of contagious diffusion.
Lastly, hierarchical diffusion occurs when an idea or innovation leapfrogs from one individual, group or location to another without affecting the spaces in between. For instance, a culture may spread from one urban center to another through communication technologies and then trickle down to the rural areas in between. The spread of fashion is a good example of this, according to Montgomery County Community College.