Contiguity

A contiguity is a series of things in contact or in proximity, or the state of being such a mass or series.

A cluster of genes which are close to one another at a chromosome locus are called contiguous. Contiguous gene disorders result from deletions or duplications of a chromosome segment that cause a contiguous gene imbalance. Also, Contiguity refers to the way Taxonomy is ordered and formed after Charles Darwin wrote Theory of the Origins of Species in 1859. Before then, scientists used a more strict taxonomy based upon an organism's locomotion and mobility. Now science bases taxonomy on contiguity, tracking changes in an organism's anatomy over eons to show contiguous shaping over time.

Memory elements are contiguous if adjacent and apparently connected (but they may, in fact, be disconnected). A computer file or other data stored on a mass storage system, particularly hard disk-based, is said to be contiguous—sometimes, ungrammatically, to be composed of one fragment—if the file data is in one continuous region without intervening extraneous data. A non-contiguous file is said to be fragmented, and can usually be defragmented with a software utility.

Political or geographical land divisions that, as a group, are not interrupted by other land or water are 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 the United Kingdom, Ireland, Sweden, Finland and Cyprus (these being non-contiguous), or the "contiguous United Kingdom" referring to all parts of the country excepting Northern Ireland (it being geographically non-contiguous).

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.

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