Geographic contiguity
Geographic contiguity is the characteristic in geography of political or geographical land divisions, as a group, not being interrupted by other land or water. Such divisions are referred to as being contiguous. In the United States, for example, the "48 contiguous states" excludes Hawaii and Alaska, which do not share borders with other U.S. states.
Other examples of geographical contiguity might include the "contiguous European Union" excluding member states such as Ireland, Sweden, Finland, Malta and Cyprus, or the "contiguous United Kingdom" referring to all parts of the country excepting Northern Ireland.
Two or more contiguous municipalities can be consolidated into one, or one municipality can consist of many noncontiguous elements. For example, the Financially Distressed Municipalities Act allows the commonwealth of Pennsylvania to merge contiguous municipalities to reduce financial distress.
Geographic contiguity is important in biology, especially animal ranges. For a particular species, its habitat may be a 'contiguous range', or it might be broken, requiring periodic, typically seasonal migrations. The same concept of contiguous range is true for human transportation studies in an attempt to understand census geography. It also comes into play with electoral geography and politics.
