Even back before the Depression, American railroads were reeling. New competition, bad luck and suffocating federal regulations were the problems. The aftermath of World War I had brought a rush to car ownership and an agricultural crisis wiped out freight transportation. ICC regulations kept the railroads from responding to the market. Then came the stainless steel streamliner, the one they'd soon be calling the Zephyr, among other evocative names. It was powered by a diesel engine, not steam. Its sleek form maximized high-speed performance, as did its lightweight construction. The railroads ordered dozens. Passengers flocked to them. The Zephyr alone maximized its passenger traffic and cut its costs by 50 percent over its steam-driven predecessors. As the new trains' popularity soared, the Zephyr starred in Hollywood's original "Silver Streak," and there was no stopping the public's desire to take the train and go. The Zephyrs matched their elegant look with sophisticated service. Menus were elaborate, seats reclined, lights were recessed, schedules were fast. Industrial designers liked the look and began to incorporate streamlining into their products - from toasters to tractors. Things changed again not long after World War II ended. The nation again turned its focus to the automobile, but this time, the interstate highway system was begun. By the 1960s, passenger trains were in dire straits. PBS-TV's "American Experience" looks back at the heyday of passenger rail travel in "Streamliner: America's Lost Trains" on Monday, Feb. 5, at 9 p.m.