“The gentle reader will never, never know what a consummate ass he can become until he goes abroad,” Mark Twain observed in “The Innocents Abroad,” a rollicking account of his 1867 expedition through Europe and the Middle East. The book’s exquisite pillorying of snobbish contemporaries who traveled through Europe collecting ostentatious manners and fashions, along with Twain’s impish use of irony and understatement, secured his reputation as an original and unabashedly American writer. It also established Twain as a masterful storyteller – one of the most companionable traits of good travel writers.

Thus it is a pure pleasure to read “Mark Twain on Travel” (The Lyons Press, 278 pages, $24.95), a collection of excerpts from his book-length works “The Innocents Abroad,” “Roughing It,” “A Tramp Abroad,” “Life on the Mississippi,” and “Following the Equator.” The recollections here span Twain’s five decades as a traveler, from an account of stealing away on a Mississippi steamboat as a young boy to his globe-spanning journeys of the late 19th century.

Though Twain is an able guide, describing exotic scenery and sites to the folks back home – Hawaii’s coconut trees, he concludes, look like feather dusters stuck by lightning – he excels as a witness to human foibles. His trenchant observations run from the minute (the wretched night watchman he meets on the Mississippi steamboat uses profanity “so devoid of art that it was an element of weakness rather than strength in his conversation”) to the profound. In Australia, he compares the willful extermination of aboriginals to the conquest of America and dryly concludes, “There are many humorous things in the world; among them the white man’s notion that he is less savage than the other savages.”

Twain reserves some of his best writing for his methods of transportation. Throughout his travels, he expends dozens of pages describing his horses, which are epically stubborn, lame, stupid, or lazy – and sometimes all of the above. And his account of traveling from Missouri to California aboard a dissolute stagecoach carrying mail remains one of the most exhilarating journeys put in writing. It offers a glimpse of America’s expanses just eight years before the completion of the transcontinental railroad forever changed the way distance was perceived on this continent.

It should come as little surprise that a former steamboat pilot would approach travel with an eye to transportation. But Twain reminds us of the adage that sometimes the journey is the destination – a valuable lesson in this era of quick and seamless arrivals. Here he is crossing America stretched out on a makeshift bed of mailbags, his trusty pipe in hand:

The stage whirled along at a spanking gait, the breeze flapping curtains and suspended coats in a most exhilarating way; the cradle swayed and swung luxuriously; the pattering of the horses’ hoofs, the cracking of the driver’s whip, and his ‘Hi-yi! g’lang!’ were music; the spinning ground and the waltzing trees appeared to give us a mute hurrah as we went by … we felt that there was only one complete and satisfying happiness in the world, and we had found it.

In 1953, the renowned American naturalist Roger Tory Peterson and his British colleague James Fisher embarked on a trek around the perimeter of North America to explore the continent’s vast nature reserves. “Wild America,” their account of the whirlwind, 100-day tour, has since become a classic of both nature and travel writing. It has also served as inspiration to future naturalists, including writer Scott Weidensaul, who poured over “Wild America” as a boy.

In “Return to Wild America: A Yearlong Search for the Continent’s Natural Soul” (North Point Press, 372 pages, $25), Mr. Weidensaul bravely offers an addendum to the work of his childhood heroes by traversing the continent – from Newfoundland to Mexico to Alaska – some 50 years later on a similar quest. But his goal is slightly different, as indicated by title of his book, which serves both as a statement of purpose and a request. “Return to Wild America” is a poetic celebration of the natural world, but it is also a fervent and powerful call to readers to reevaluate the importance of nature in their own lives.

The story that Mr. Weidensaul tells is often one of restoration and conservation that surpasses anything that Fisher and Peterson saw in their travels. In California, he excitedly observes the return of sea otters and the magnificent condor, a relic of the Ice Age with a wingspan reaching up to 10 feet. In the Florida Keys, he reports on the creation of Dry Tortugas National Park, a nature re serve rich with coral reefs and migrating birds. In the Everglades, he celebrates the estimated $8 billion Everglades Restoration Plan, which will be one of the world’s most ambitious restoration projects – if it is ever completed. And he finds a group of innovative community activists working to conserve the extraordinary cloud forests of Mexico’s Sierra Madres.

Mr. Weidensaul is also keenly aware of what has been lost in the five decades since “Wild America” first appeared. He observes the increasing encroachment of a human population whose demands on nature are relentless: the “mansionization” of the Northeast and mid-Atlantic region, which leaves wildlife stranded in puzzle-like formations of undeveloped land; the sapping of rivers and streams throughout the country for agricultural use; the suburban expansion that threatens the famous bird populations of the Rio Grande. It’s enough to make Mr. Weidensaul wonder “whether our hearts are too small to embrace an America as complete as we can make it.”

One of Mr. Weidensaul’s most important aims is to debunk the romance of “wild” America as land that is completely free and unhindered. In fact, wilderness must now be monitored, manipulated, reseeded, repopulated, weeded, and subjected to all sorts of mechanizations in order to reach a seemingly pristine state. “The days of ‘letting nature take its course’ are long gone,” he writes. Wild America is no longer a state of being; it is a constant effort. And although Mr. Weidensaul meets scores of conservationists and naturalists during the course of his travels – people who are shouldering the hard, complex, and sometimes tedious work of maintaining America’s wilderness – the ultimate accomplishment of this task depends on the rest of us.