In the 1930s, “streamlining” locomotives came into popular use. To increase locomotive speed,streamlining designs promoted aerodynamic engine shapes that would slice more easily through the wind at high speeds. The PRR GG1 is the most popular example of such an engine, and ushered in an era of fast, reliable, and popular train service.

Between 1934 and 1943, General Electric and the Pennsy’s Altoona Works built 139 GG1s, the last of which was retired in 1983. The engine remains popular as an icon of American railroading in advertisements.