Canal instincts: George Washington once dreamed of turning America into a new Venice.

• Author: Clymer, Adam

Contemporary presidents come to be judged in broad strokes, though different partisans have different brushes--George W. Bush as moral and resolute, or as dogmatic and incurious; Bill Clinton as immoral, or as caring. Comparable contemporary disputes are more a kind of background noise when we measure those we know only from history books and biographies. They settle in our minds for an attribute or two that fit together, though sometimes we acknowledge the complexities or contradictions in a slaveholding Thomas Jefferson proclaiming the equality of man or an experimental Franklin Roosevelt, committed not to any fixed principle (except perhaps a healthy skepticism toward his own class), but to finding solutions from all kinds of sources.

George Washington has been the subject of less recent historical redefinition than his contemporaries Thomas Jefferson and John Adams, or his latter-day successors Dwight Eisenhower or Harry Truman. For years, Washington has been depicted, almost uniformly, as sober, brave, and dedicated, as a gentleman concerned with maintaining a good reputation, as perhaps a bit fussy, but above all, as virtuous. And perhaps a little dull.

In his new book, The Grand Idea: George Washington's Potomac and the Race to the West, Washington Post writer Joel Achenbach does not upset those impressions. His Washington is as serious as the man described in Douglas Southall Freeman's acclaimed 1948 biography, or in the historian James Thomas Flexner's admiring four-volume series on the first president. Achenbach acknowledges that his book tells a story that has been recounted by other scholars. But this book reveals a dimension of the man not often seen--that of Washington as a dreamer. The retired general imagined and then traced a route west to bind the Appalachian wilderness to the coastal states even before the 13 former colonies were themselves bound to one another.

The route Washington thought could connect the coast to the West was the Potomac River, whose headwaters, at least on a map, were not out of reach of the tributaries of the Ohio River. Achenbach is at his best in communicating to an age of interstate highway drivers why water was the only way for people to go any distance at all in the 18th century. "Roads in America were often hardly more than trails, choked with stumps," he writes. "Throughout the United States, bridges over major rivers simply didn't exist." In the back country, where Washington journeyed in...