A Chorochromatic map (from Greek χώρα chóra 'region' and χρώμα chróma 'color'), also known as an area-class, qualitative area, or mosaic map, is a type of thematic map that portray regions of categorical or nominal data using variations in color symbols. Chorochromatic maps are typically used to represent discrete fields, also known as categorical coverages. Chorochromatic maps differ from choropleth maps in that chorochromatic maps are mapped according to data-driven boundaries instead of trying to make the data fit within existing, sometimes arbitrary units such as political boundaries.

The chorochromatic map is one of the oldest types of thematic map, first appearing independently in several different fields. In 1741, Gottfried Hensel published Synopsis Universae Philologiae, a book about world languages that included a set of maps of language regions, each with boundaries and colors for broad language families as he understood them. Other maps of cultural regions began to appear in the 19th Century.

The first known geological map of surficial rock types was published by Jean-Étienne Guettard and Philippe Buache in 1746, showing matching formations crossing the English Channel in bands of gray. In the early 19th Century, these kinds of maps proliferated, especially in the United Kingdom and France, including hand-painted color.

Perhaps the first master of this technique was Heinrich Berghaus. His 1837 Physikalischer Atlas, probably the first thematic atlas ever published, includes several color chorochromatic maps. These included a variety of topics from both physical and human geography: watersheds, geology, agriculture, biogeography, and ethnicity. Much of the data was apparently obtained from Alexander von Humboldt.

With the increasing availability of chromolithography in the second half of the 19th Century, chorochromatic maps proliferated to the point that the concept of filling areas with color became almost mundane. The origin of the term chorochromatic is unclear, as none of these early works mentioned it; Erwin Raisz uses the term in the 1938 textbook General Cartography.

As the rise of academic cartography focused attention on the design of thematic maps to represent statistical data, maps of qualitative information received little direct research. The chorochromatic form was acknowledged as a useful technique for portraying the results of geographical analysis. More research has been conducted in the era of geographic information science (starting in the 1990s) on the underlying concepts and data models of discrete fields, notably issues of vagueness that are inherent to the spatial manifestation of categories.

A chorochromatic map is a visualization of regions, with a nominal (qualitative) difference between them. In many cases, these regions are distinct established entities; for example, a map of land administration in the United States would include features such as national and state parks.

The second type of phenomenon that is commonly represented in chorochromatic maps, which may be the basis of more maps than the first type, is what Daniel Montello calls a thematic region. This type of region is the spatial manifestation of category. That is, it is the area in which a given type of phenomenon is present; for example, the area in which a particular type of plant is predominant or where the majority of residents primarily speak a given language. Since most geographical phenomena exhibit a tendency for spatially proximate phenomena to be similar (i.e. Tobler's first law of geography), it is common to see most or all locations around one location be of the same category, whether that is climate or socioeconomic status, resulting in a relatively homogenous region.