(FORTUNE Magazine) – Trucking is one of those industries both wonderfully grand and stupefyingly tedious at the same time. The wonderful part: Massive, dazzling, chrome-plated trucks pushed down the highway by burly guys with cowboy boots and giant belt buckles. More than 1.6 million over-the-road rigs with $150 billion in revenues, hauling 60% of all the freight moved in the country. Multibillion-dollar trucking companies with fantastic central dispatching centers that the Strategic Air Command would envy. Enormous truck stops along barren stretches of highway that haven't shut their doors for an hour in 30 years. The undulating all-night hum of an Interstate highway throbbing like a giant machine. The flip side: truck stops full of lonely drivers with faraway stares, the unrelenting competition, the low pay, the weeks away from home, thieving brokers, cheesy motels, sleeping in the cab, and too many baloney sandwiches.

The industry is healthier than it was a few years ago, but that's not saying a lot. For much of the mid-1990s the trucking industry was a multiple-injury wreck. Back then, trucking companies were still adjusting to the ongoing state-by-state deregulation of routes and rates. Tens of thousands of tiny new trucking companies had sprung up, eager to get into the business, squeezing margins for everybody. The economy was soft, expected new truck traffic to Mexico didn't materialize, the railroads were siphoning off business, and everything from floods to blizzards impeded travel.

Lately, though, big companies have learned how to restructure operations to accommodate the changing demands of shippers. The strong economy has helped too. And problems on the Union Pacific railroad have sent demand for trucks into high gear. As a result, margins last year were up sharply over 1996, and the once-battered stock prices of several giant trucking companies have soared in the past year. All eight trucking companies on this year's FORTUNE 500 list eked out a profit during 1997, and several enjoyed big earnings gains. Roadway Express earned a skimpy $37 million on revenues of $2.7 billion, but that represented a 69% profit increase from 1996. USFreightways pumped up profits 80%, to $18 million on revenues of $1.6 billion. The industry's biggest winner last year, CNF Transportation, pushed earnings up by a stupendous 339%, posting a $121 million profit on revenues of $4.3 billion.

Of course, it's hard to make blanket statements about a $150 billion industry with as many layers and compartments as the trucking business. Gigantic United Parcel Service mostly delivers just a package or two at a time and owns 80% of that part of the business. Companies like Yellow Corp. and Consolidated Freightways occupy another niche. They specialize in partial loads, their trucks hauling perhaps a half-dozen five-ton loads for a half-dozen customers at a time. Other giants like J.B. Hunt and Schneider National run long-haul fleets with thousands of trucks that carry a full load for a single customer at a time. And 300,000 independent truckers are constantly barreling around the country, hauling a truckload of cauliflower today and windshield wipers tomorrow, for whatever money they can negotiate.

If anybody got hit hard by the deregulation of the past decade, it was carriers like Yellow, Consolidated, and Roadway Express. For eons they fared well, thanks to elaborate communications and dispatching systems and well-paid, unionized work forces with little turnover. But the shift by manufacturers to just-in-time inventory systems required them to make painful adjustments. These less-than-truckload companies each operated extensive networks of hundreds of warehouses, where they consolidated a bunch of partial loads into efficient full loads, sent a truck hundreds or thousands of miles, and then broke the load up again. Alas, all that consolidating could double the time it took to deliver a load. Impatient factory managers turned to the growing number of independent truckers who worked for less and were willing to make a beeline from suppliers to the factory. After years of marginal or nonexistent earnings, most of the big less-than-truckload companies finally shut down their warehouse networks and began making speedier deliveries without a full load.

The big single-load operators like J.B. Hunt and Schneider National had to swallow hard and make painful changes in how they operated as well. For years the railroads have been their bitterest rivals: To thwart efforts to get bigger trucks on the road, railroads have funded an organization called CRASH that emphasizes the dangers of heavy trucks on the highways. Hunt and Schneider slowly recognized that railroads' intermodal operations were siphoning off more and more of their long-distance hauls by putting truck trailers on flatbed railcars. Rather than resisting, they agreed to work with the railroads, building truck-train facilities near big switchyards and signing long-term contracts to ship trucks by rail.

Hunt also benefited from a dramatic step it took a year ago to cut the high driver-turnover rate that bedevils all big fleets. (About 350,000 truckers change employers annually.) The solution was simple: It boosted drivers' pay by 33%. As a result Hunt was able to recruit more-experienced workers with good safety records, and saw margins improve. The company's stock price has nearly doubled since January.

It is the image of the solitary, independent long-haul truck drivers, however, that conjures up much of the romance of the trucking industry, and their numbers have soared since deregulation began. More than 300,000 of them are out there, trying to make ends meet, scrambling to find their next load, and, if they've been on the road for weeks, praying that load will bring them closer to home.

Tough as the job is, it will always appeal to thousands of men. Behold veteran driver Richard Kershman climbing behind the wheel of his 460-horsepower 18-wheeler. Suggest that he could quit driving and start a business selling all the technical know-how he has amassed on the road, and you will be met with ferocious scorn. "What? Give this up? I wouldn't want to prostitute myself."