Blues
ColorBrewer 2.0 (Brewer & Harrower)
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#eff3ff -
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#08519c
On a map
A synthetic demo grid, classed with equal intervals — the point is the palette against real basemap ink, not the data. Switch themes to see how much basemap the palette leaves room for.
Metadata
Provenance
Blues is one of the single-hue sequential schemes from ColorBrewer, the palette system built by cartographer Cynthia Brewer with Mark Harrower at Penn State and published online in 2002. ColorBrewer came out of research into how people actually read thematic maps — the schemes were tested for legibility on screen, in print, on LCD projectors, and under color vision deficiency, and each one is annotated with where it holds up. It remains the most widely used cartographic palette set in existence, and its Apache-style license asks only for attribution.
When to use it
A single-hue ramp like Blues is the quietest way to show one numeric variable: lightness carries the whole message, so it is nearly impossible to misread the direction. Use it for choropleths of rates, densities, and counts where the map has other things to say — labels, boundaries, a second layer — and the data should not shout. The pale low end sits almost invisibly on a white basemap, which is exactly what you want for zero-inflated data where most polygons are near-empty.
License
Apache-style ColorBrewer License (attribution required) · source
The color specification carries this license, which is separate from the MIT license on this site. See attribution.