That arrangement was consistent with the habit of many texts and reference books, which tended to use blue for Republicans in part because blue was the color of the Union in the Civil War.

While the thrill of being a fly on the wall for these historic hours provides the core of Kaplan’s undertaking, the book’s most enlightening ... told him to come on over to the Harlem ...

Red is obviously terrible. Purple is even worse. NPR's Neda Ulaby tells us how purple came to be a scarier color than red. NEDA ULABY, BYLINE: Red is the traditional color of danger, of stop signs ...

Almost every expression of color in the natural world came about to signal, or obscure, a creature to something else. For instance, "aposematism" is color used as a warning—the butterfly’s ...