What is graham flour, used in "Graham Crackers", made from?

Graham flour, used in true Graham crackers, is made from unsifted, coarsely ground whole wheat flour. It contains the wheat grain’s bran, germ, and endosperm rather than removing the outer layers to produce refined white flour.

Its name comes from Sylvester Graham, an American Presbyterian minister and dietary reformer who lived from 1794 to 1851. Graham criticized the highly refined white flour becoming common during the Industrial Revolution and promoted flour made from the entire wheat grain. Graham flour differs from ordinary whole-wheat flour mainly in its milling: the endosperm may be finely ground, while the bran and germ are ground more coarsely and then recombined.

That coarse texture gives Graham crackers their characteristic hearty flavor and slightly rough crumb. Modern commercial Graham crackers may use flour blends, sweeteners, oils, and other ingredients, so they do not always represent the simplest historical recipe. The word “Graham” refers to the flour’s style and namesake, not to a separate species of wheat or a flavoring ingredient.

A closely related term is whole-grain flour, which also retains the bran, germ, and endosperm, though the texture and milling method can differ.