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nOnTRaDiTiOnaL MaPPing
by-area cartogram.) Within this type are several subcategories that are discussed
below.
A second type of cartogram uses a time scale instead of a distance scale; these are
sometimes called
distance cartograms or
linear cartograms. At one time, any spatial
diagram or model was called a cartogram; Raisz described “timetable cartograms”
that showed transportation routes as a cartogram, but they are more properly called
diagrams.
Value-by-area Cartograms
COnTigUOUs CaRTOgRaMs
Contiguous cartograms attempt to maintain borders
between enumeration areas
although shapes are distorted. The
rectangular cartogram maintains borders, but not
shapes; the shapes of areas become squares and rectangles.
A type of contiguous cartogram that has become more popular since the advent
of computers is the topologically correct cartogram. This was a very difficult task
to perform before the advent of computers. Figure 10.2 is a hand-drawn cartogram,
and Plate 10.1 is a computer-generated cartogram. The maps are highly abstracted
representations on which actual locations or outlines are distorted and even the rela-
tionships between areas may be distorted. Although the border relationships are
