Unfold a map of the United States and it is possible to see everything and nothing at once. Colored swatches contoured by black boundary lines; state names and cities in boldface type; fine print and pinpoint markings for the places where most of us spend our lives.
But the faces of the people are absent, their history invisible. The look of the hills and rivers, the slow-passing clouds, the arduous hours required to get from here to there - most individuals cannot read these from a map. But William Least Heat-Moon is not like most individuals. Author, naturalist, professional wanderer, he can recognize the lifeblood hinted at by these winding miles. It is a hard-earned form of knowing.
In 1982, Mr. Heat-Moon became a literary sensation with ''Blue Highways,'' an account of his 13,000-mile circumnavigation of America by its back roads - those pale blue squiggles on the map. Acclaimed by writers like Robert Penn Warren, the book became an international bestseller and provided Heat-Moon the freedom to pursue his self-assigned examination of America.
His second great journey culminated in ''PrairyErth'' (1991), what the author calls ''a deep map'' of Chase County, Kan., ''the last remaining grand expanse of tall-grass prairie in America.'' Slowing his exploration to a walking pace, he crisscrossed a mere 774 square miles of land, investigating the geography, history, and legend of a single county and the lives of all 3,000 of its human inhabitants.
In the summer of 1994, I sat in a restaurant on Block Island, R.I., as Heat-Moon shared his plan for a third great expedition. He had decided to cross the heart of the continent from Atlantic to Pacific, ''over 5,400 miles with water beneath you nearly all the way.'' It was by river that explorers first ventured out across America, and for more than a century rivers provided our means of commerce and travel. When they were eclipsed by speedier modes of travel, they were ignored and became little more than conduits for sewage. The Clean Water Act of 1972 reversed that trend and now, Heat-Moon says, the health of our rivers is a barometer for the environmental well-being of our nation.
Unlike his earlier projects, this was not to be a solo trip. Even an experienced seaman would need a second pair of eyes and hands to cast off and moor safely, read maps, navigate tricky waters, and negotiate 88 dams. So Heat-Moon, a novice, was inviting several friends to accompany him on each portion of his trip.
'I should have brought an atlas along so you could really see the whole of it,'' Heat-Moon explained, excitement rising above his normally stolid demeanor. As he quickly sketched a wobbly silhouette of America on a paper napkin, I watched the journey take shape: from the Atlantic up the Hudson and across New York on the Erie Canal. A 50-mile sprint across the lower part of Lake Erie would bring him to the Pennsylvania shore and back on inland water. After a portage to Lake Chautauqua, he'd reach the Allegheny River, then ''the rest of the route would be big-water passage.''
One inky stroke meant the Ohio River, another the Mississippi, and a long winding arch the 2,500 tortuous miles of the Missouri. He would cross the Continental Divide by portaging from the Beaverhead River in Montana to the Lemhi in Idaho, then head down the Salmon, Snake, and Columbia Rivers to the Pacific. The passage would touch on 24 bodies of water and two oceans, with only 120 miles crossed on land.
He had spent more than a year researching the project, logging more than 15,000 highway miles checking routes, collecting charts, scouting potential danger areas. But days before his journey was to begin, he still had doubts. ''The only way you could make it through,'' he decided, ''is to do one day at a time. And even though you have to plan ahead, try not to look ahead.... It's a marathon run; you're not thinking about the finish line. You'd better just think about the next hundred yards.''
And so on the bright morning of April 20, Heat-Moon and crew began the voyage aboard the 22-foot flat-bottomed C-Dory he named Nikawa (''River Horse'' in the Osage language). He cast off from Elizabeth, N.J., cruised through Atlantic waters beyond the Verrazano Narrows and then north past the Statue of Liberty toward the Hudson. Strapped on top of the Nikawa's cabin was a kayak, and a third boat, a 17-foot canoe, was secured to a support vehicle that would shadow much of his journey.
On Lake Erie, a storm battered the boat so badly, the crew feared the hull might split. On the Mississippi and Missouri Rivers, heavy spring rains had created flooding. One evening, with light failing and no place to dock, Heat-Moon dropped anchor in one man's front yard. He ''came out on the front porch and stared at us, scratching his head,'' Heat-Moon recalled later. But as so often on his journey, people generously offered what help they could. ''He brought us into the house, cooked us a marvelous catfish meal.''
When I flew into Idaho to join Heat-Moon, only two rivers separated the Nikawa from the Pacific tides. Entering Washington, we moved down the Snake River and into the great Columbia - high, dry hills scarred with ancient volcanic flows bordering us on either side.
We prepared to leave the port of Kennewick, Wash., beneath a sky of dark scudding clouds. A friend visited the Coast Guard station to check the weather report, returning with good news: ''skies clearing, waves 1 to 3 feet, wind 10 to 15 miles per hour.'' But our messenger neglected to mention the last few words of the bulletin: ''with gusts increasing to 40 m.p.h.'' We had not gone five miles before the wind had intensified to a steady blow and the Nikawa was crashing against five- and six-foot waves bunched so close together we would hardly regain our balance from one bludgeoning to the next. Our heads cracked against the cabin ceiling and we were tossed around like cowboys on the back of a wild bronco.
I madly scoured the charts for a safe haven. We made for a small cove on the starboard shore where we hoped to wait out the storm. Suddenly we felt the jolt-grind of hull against gravel: We had run aground. With the wind still swirling, we stripped off our pants and climbed into the cold Columbia, using our backs to inch us off the bar. When we were free, Heat-Moon steered us gingerly toward the lee shore where we beached the boat on the sand.
We were marooned for seven hours, silently thankful to be seated on dry ground with our boat intact. When the wind finally abated and the water level went down, we found we'd wandered across the streets and stone foundations of the town of Hover, Wash., flooded when the Columbia was first dammed. Any one of these jagged walls could have torn the heart out of the Nikawa.
On Aug. 2, 102 days after he left New York, William Least Heat-Moon piloted the Nikawa down the Clifton Channel into Astoria, Ore., his final Western port. By all rights, the trip could have been called complete. But Heat-Moon had set his sights just a bit farther out. The Columbia Bar is the point offshore where river current and ocean tide meet. Navigational charts rank it the third-most-dangerous river entrance on Earth. The remains of 1,000 ships litter the ocean floor here. But only here could Heat-Moon claim to have gone from ocean to ocean.
The Nikawa was led out by Ralph Gilbert of the Coast Guard Auxiliary on seas he called ''the calmest I've seen for weeks'': It was a roller-coaster ride of swells so high, you'd lose all sight of the boats around you. Going down, all you'd see is roiling green; riding up, only sky. We finally reached buoy No. 8, and Gilbert's voice crackled over the radio: ''Nikawa, this is the Pacific.''
I took the wheel while Heat-Moon made his way to the stern. He lifted a small bottle of saltwater he'd filled in the Atlantic on the first day of his voyage. As the boat rocked wildly, he poured the water slowly over the side. Then, both arms raised toward the sky, he gave a silent thank you.
Now we were truly done. Or at least I was. Heat-Moon would have to take this journey, all 5,400 miles of it, one more time. With his carton of maps and pamphlets, and 400 pages he'd written in his daily log, he will spend several years distilling all he saw and learned from his watery vantage. I recalled a small driftwood placard I'd seen on the door of the harbor master's office at Cathlamet, Wash., the day before we reached the Pacific. ''Some of man's most important journeys merely take him to quiet places where he can look skyward and dream his dreams.'' And chart the way home.