The collaboration between Raymond Loewy and the Pennsylvania Railroad (PRR) was a fruitful one. The PRR was, for several years, the biggest railroad company in the USA, controlling, at its peak, more than 16 000 Km (10 000 miles) of rail line and employing over 250 000 workers. It has been said that the president of PRR at the time was considered more powerful than the country's president himself. In 1934, the company built a locomotive that would become the touchstone for locomotives worldwide - the GG1, a two-way electric traction unit, that was to become a model followed by many other locomotives still in use today. Contrary to popular belief, the GG1 was not designed by Loewy. His contribution came later on, when he suggested the use of a smooth, welded construction instead of riveted assembly, in order to streamline its shape and construction. This would prove to be the begining of an amazing ride.
In 1937, when the PRR decided to build a new experimental steam locomotive, Loewy was hired to design it. He designed a powerful machine in a streamlined aerodinamic style, called S1 and nicknamed The Big Engine. Even when motionless it seemed fast and, indeed, it was. However, it was never able to reach the kind of performances that were expected from it: it was never able to haul 1 000 tons at 160 Km/ hour (100 miles/ hour). It first run in 1939, but was removed from the tracks in 1945. Still, the S1 remains, to this day, the archetype of modern industrial design, setting standards that would prevail for most of the 20th century.
The partnership between Loewy and the PRR would also produce the T1, PRR's largest, most powerful and impressive steam locomotive, able to haul 1 000 tons at 160 Km/ hour easily - in fact, it was so powerful it was extremely prone to violent wheelslip. The T1 was a superb machine, with over 6 000 Hp and of complex and sophisticated technology. Two prototypes were introduced in 1942 and fifty copies in 1946. Although a lot of hope was set on the T1 and it was seen as a prototype for the future of high-speed, long-distance transportation, problems concerning its reliability and maintenance jeopardised its continuity. It was finally removed in 1948, which, also, signaled the arrival of diesel locomotives.