Unlike most incorporated places, CDP boundaries are delineated to follow visible features (streets, roads, rivers, railroads, and the like) except where the boundary of the potential CDP is coincident with the boundary of an adjoining legally recognized entity, such as an incorporated place or MCD. Because of this requirement, sparsely settled area sometimes is included in a CDP, or conversely, a small fringe of built-up area is not included in the CDP. The latter is particularly is true in relatively small CDPs where outlying roads or features that may be used as boundaries are spaced widely.
Ideally, CDPs contain a dense, city-type street pattern and have an overall population density of at least 1,000 people per square mile. However, the Census Bureau recognizes that some CDPs may not meet the density criterion because the selection of available boundary features may result in the CDP including some sparsely settled territory. Another exception to the density criteria may occur on American Indian reservations, where communities often have a dispersed settlement pattern. Several minimum population sizes apply to CDPs recognized in the 1990 census, but there is no maximum limit to the number of people a CDP may contain.
The minimum population size for most CDPs located within UAs is 2,500. However, because preliminary 1990 population counts were used to qualify CDPs, some CDPs inside UAs have less than 2,500 people. (For details, see Chapter 12, “The Urban and Rural Classifications.”) This 2,500 population size threshold does not apply to Hawaii, Puerto Rico, or the Outlying Areas.
The minimum population size for most CDPs located outside of UAs is 1,000 people; for CDPs on American Indian reservations, it is 250 people. These sizes do not apply to Alaska, Hawaii, Puerto Rico, or the Outlying Areas.
Alaska is by far the most sparsely settled of the States, and has very few communities with more than 1,000 residents. To account for the significance of, and allow for tabulation of, data to identify the smaller communities in Alaska, the minimum population for CDPs outside of UAs
