Wikipedia:Using maps and analogous media: Difference between revisions

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{{Essay|WP:MAPCITE}}

{{Nutshell|[[Map|Maps]]s and [[Lineline chart|line charts]]s used as illustrations followare theequally samesubject rulesto asthe picturesguidelines that are used asfor illustrations.|Maps and line charts may be used as sources, butare equally subject to the core content policies of [[WP:V|Verifiabilityverifiability]], and [[WP:NOROR|Nono original research]] still apply.|It is not [[WP:OR|original research]] to extract information from a map or line chart using standard techniques, particularly if those techniquesemployed areacross common to two or moremultiple disciplines.|The core content policies of [[WP:V|Verifiability]], and [[WP:NOR|No original research]] apply to user-made maps.}}

[[File:1930 D&RGW WP.jpg|thumb|300pxupright=1.35|This map is a commercial map of the [[Denver and Rio Grande Western]] and [[Western Pacific Railroad]]s as they existed in 1914. This map is valuable as a source of information and as illustration for what it depicts. The map depicts the general route of the two railroads advertised, the route of their primary rivals, several long abandoned [[short line railroad]]s and short-lived mining [[boomtown]]s in the [[western United States]], and this map is used appropriately in articles about these subjects. However, the map's limitations should also be understood. Comparing this map with others will reveal that this commercial map is drawn on an inconsistent scale, perhaps to minimize the fact that the competing [[Overland Route (Union Pacific Railroad)|Overland Route]] is more direct than the route of the railroads advertised.]]

Any map or line chart used in Wikipedia should conform with Wikipedia's policies of [[WP:neutrality|neutrality]], [[WP:reliabilityverifiability|reliabilityverifiability]], and [[WP:verifiabilityNOR|verifiabilityno original research]]. Maps can be used for two purposes in Wikipedia articles, as sources or as illustration. Regardless of the point of using a map in an article, the following points should be kept in mind:

*The presence of an object on a map is not sufficient by itself to show [[WP:notability|notability]] of a subject.

*Even maps produced using reliable sources (such as [[GIS]] data) can have minor errors as a result of errors in the underlying database, or the cartographer trying to overlay data from two non-linear sources. Minor map errors are common, for that reason any map detail that is key to the article should be confirmed with a separate map from a different publisher. Rarely are map errors notable, even if they have gone uncorrected for decades.

*Many cartographers intentionally introduce minor errors in inconspicuous locations as a form of [[copyright trap]]. Likewise, rarely are such introductions notable.

*Many companies publish a yearly edition of a map, and include the year as part of the title (e.g. 2009 Road Atlas). As these have to be drafted in advance, often times the cartagrophercartographer will draw projects under construction as completed, or proposed projects as under construction. This is an effort to increase the shelf life of the map, so as to not be obsolete before the year on the edition name has finished. (e.g. a highway expected to be completed by 2009 may be drawn as complete in the 2009 edition, even though it was still under construction when the map was drafted) This can introduce another source of error in an otherwise reliable map, should a project be cancelled or significantly changed. Such errors can be detected by comparing multiple editions of the same map.

*Any cultural bias apparent in a map should be clearly explained in a neutral fashion. For example, Wikipedia's article about the [[Falkland Islands sovereignty dispute]] features side-by-side maps showing the rival naming conventions used by [[Argentina]] and the [[United Kingdom]] for the named features of the islands, without implying one is correct. In cases where it is not practical or possible to show maps from each POV in a boundary or sovereignty dispute, a caption should explain which details of the map are disputed.

*Editors who use maps should be aware that maps covering large areas almost always have one type of distortion or another, depending on the [[map projection]] used. Care should be taken to select a map whose projection is appropriate for the purpose to which it is being put.

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===Original research===

Use of a map to source information beyond the intended use of a map can violate Wikipedia's policies, such as [[WP:OR|no original research]], [[WP:V|verifiability]] or [[WP:reliability|reliability]]. For example, if an object does not appear in the 1950 and earlier editions of a map, but does appear in the 1951 and later editions of a map, this does not prove the year of construction was 1950, unless there is additional information in the map, as this is using the map in a different manner from its intended purpose. ItThere are two potential flaws with using maps in this manner. First commercial maps are sometimes drafted in advance of the edition date. Second, commercial maps sometimes draw projects expected to be completed during the edition year as complete. Government and non-profit maps are more likely to list cartography and effective dates and are less likely to include anticipated details in a map verses commercial maps. In any case, it would be acceptable to say "The freeway first appeared on the department of transportation's map in 1951" or "The freeway was constructed by 1951" (assuming the source has a reputation for accuracy in its map updates) in the above case. Some maps are totally unreliable if used in a manner for which they were not designed. For example, maps of mass transit systems are usually not drawn to a scale, as they are drawn to show the interconnections of a system in such a way that the map will fit in a limited space. This makes such maps unsuitable for other uses. For example, the [[Tube map|London Underground Map]] is an unreliable source for estimating the distance between two stops, but it is an excellent source for the number of stops on a given route.

When using maps as a source for topographic descriptions, care should be taken not to read more into the map than is already there. It is quite in order to state the “Valley X is ‘U’ shaped with [[glacial moraine]] at its entrance”, assuming that is what the map shows; the words “glacial moraine” should be explicitly stated on the map. However it is original research to state that “Valley X is glacial in origin” unless the map actually states that (e.g., in a caption), because there might be some other explanation for the valley's origin or the presence of the glacial moraine.

==Description==

Maps are often used to provide a description of linear features, such as a waterway, mountain range, road, railroad, or pipeline, etc., when doing so a single map should not be used the sole source used to provide the description. While a map is useful to source details in a general description section, other types of sources should also be used, if available. For some subjects the only sources available will be maps and it will be necessary to have the entire general description sourced from maps. Keep in mind that different types of information will be visible depending on the type of map used (i.e. road map, political map, topographical map, or recreational map). Ideally a map of each of those types should at least be consulted in drafting a description, if not used. For example if only a road map is used, the summary would consist almost exclusively of road features, and neglect geographical or political considerations. Using different maps of the same type (e.g. two road maps from different publishers) would likely not enhance the description, however may provide value to confirm a suspected map error or controversial detail. If a description only contains details from one map, the reader could save time by just looking at the map to get this information. The author should remember that a good article will describe an object above and beyond what is visible in a map.

== See also ==

* [[Wikipedia:WikiProject Maps/Conventions]], standard practices for displaying maps on Wikipedia

* [[Wikipedia:Manual of Style/Diagrams and maps]], an inactive style guideline proposal

* [[Wikipedia:Requests for comment/Using maps as sources]]

{{Essays on building Wikipedia}}

[[Category:Wikipedia essays about verification]]

[[Category:Wikipedia maps]]