The famous GG1 locomotive was once the workhorse between New York City , Washington DC, and Harrisburg. Initially built to haul heavy passenger trains at top speed, some were also regeared for freight service. They were introduced as part of the Pennsylvania Railroad's massive 1930s project to electrify the line (install an infrastructure of overhead electric "catenary" wires to power the engines). Electrification was the solution to moving more trains with more cars and faster acceleration than steam locomotives could handle. The catenary, partly financed by the Federal government during the Great Depression as an economy stimulus, is still used today by Amtrak. Through their lives, the 139 GG1s were painted in various colors, with the Brunswick green (almost black) the most remembered.