Freight trains are used daily to transport goods across the United States. They are a key component in the distribution of items such as coal, cars, and lumber. Trains consume 3.7 billion gallons of diesel fuel in the United States. The fuel consumption is directly related to the wind resistance (or the aerodynamic drag) of the train geometry. Reducing the aerodynamic drag can therefore lead to significant savings in cost and greenhouse gas emissions. This provides great incentive to reduce the aerodynamic resistance of trains. An examination of sources of drag on the complex geometry of a locomotive are presented in this study. Past studies have used simplified bogie (wheel and motor housing) geometries, whereas the current study includes looking at vortical structures in the near field of the locomotive. The investigation used computational fluid dynamics simulation of the unsteady Reynolds-Averaged Navier-Stokes equation with the Menter SST k-ω turbulence model to explore which locomotive components contribute the most to the overall drag. The study used a single wind to train speed ratio of one half and crosswind angles up to 30 degrees. The results were compared to the Davis-Peters equation. The results show that 75% of the total drag is from the front of the locomotive in straight on flow. The percentage of total drag from the front of the locomotive decreased to 40% as the crosswind angle increased to 30 degrees while still being the dominant source. The study also showed an unsteady vortical structure was acting on the locomotive.