There are dozens of styles of axe-head, with variations based both on function and region of manufacture. Many of these styles have stories behind them, as does the American axe-industry as a whole. Timber booms were numerous and often the only source of hard-currency for the frontier regions of the United States.
I came across this great article from The Atlantic. It traces the history of the American axe from the first settlers, through Thoreau, to the modern-day manufacturers and users who keep alive the art and traditions of this essential human tool.
From The Atlantic:
The story of the modern axe is the story of the American felling axe. Colonists arrived with European patterns—trade axes with narrow polls and bits that curved gracefully from eye to heel. They were effective on much of the timber cut across Europe but were ultimately inadequate for the vast forests and enormous trees the settlers encountered.
Aesthetically, the American axe seems crude at best. Blocky, graceless, it was the product of individual small-town blacksmiths hammering out an adequate substitute for the more elegant European counterparts. Such a depiction is, however, misleading. The innovation of the American axehead was a broad, slightly curving bit extending through an elongated eye to the flattened poll. The wider bit and heavier poll balance the head and focus the force. Nor was it just a hunk of iron. Through most of the 18th and 19th centuries, axe heads were formed in a fairly complicated process involving drawing, upsetting, and welding a bar of iron with a steel slug edge. Welding, tempering the edge, grinding, sharpening, and stropping produced an object that was functional, long-lasting, and key to the expansion of European colonists in America.
Traditionally, handles were made of new-growth straight-grained hickory, with the lengths varied in relation to the task. Attaching the handle—“hanging the axe”—was a complicated process involving plumbobs, planing, and wedging, a task usually supervised by the axe’s owner. Those graceful fawn-footed curved handles for single-bit axes did not become popular until the middle of the 19th century with the advent of contour lathes adapted from gun-stock machinery.
It is a bit of a long read, but I found it fascinating. (the end is a little hokey and melodramatic though).