Objectives

In this section, you will receive an overview of the different types of geography managed by GIS software.

Types of Geography

Regions – Refer to geographic features which can be described by a polygon. Regions can include states, counties, zip codes, census tracts, or block groups.
Lakes – Refer to "holes" in a region. For example, a city boundary which includes an unincorporated area within its boundary would contain a lake.

Islands – Refer to regions which are not contiguous with another region. For example, a city boundary in a large unincorporated area would be a geographic island since there would be no other cities adjacent to it.

Points – Refer to geographic features which can be described by a single latitude and longitude pair. Points are typically used to depict address locations. Also, points may sometimes be used to depict regions when the map is at a large scale. For example, city boundaries on a map of the entire United States would not normally be large enough for boundaries to be discernable, so they would be depicted with a point instead.

Lines – Refer to any geographic feature that can be described by straight or curved line segments. Lines are typically used to describe roads, highways, commuter patterns, rivers, streams, etc.

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