Editing Cartogram (section)

== Linear cartograms ==
[[File:Travel Time Tube Map - High Barnet.png|thumb|A linear cartogram of the London Underground, with distance distorted to represent travel time from High Barnet station|right]]
While an area cartogram manipulates the area of a polygon feature, a '''linear cartogram''' manipulates linear distance on a line feature. The spatial distortion allows the map reader to easily visualize intangible concepts such as travel time and connectivity on a network. Distance cartograms are also useful for comparing such concepts among different geographic features. A distance cartogram may also be called a ''central-point cartogram''.

A common use of distance cartograms is to show the relative travel times and directions from vertices in a network. For example, on a distance cartogram showing travel time between cities, the less time required to get from one city to another, the shorter the distance on the cartogram will be. When it takes a longer time to travel between two cities, they will be shown as further apart in the cartogram, even if they are physically close together.

Distance cartograms are also used to show connectivity. This is common on subway and metro maps, where stations and stops are shown as being the same distance apart on the map even though the true distance varies.  Though the exact time and distance from one location to another is distorted, these cartograms are still useful for travel and analysis.