The goal of this study was to conduct a comprehensive life cycle assessment (LCA) for large onshore wind turbines in the US, including all phases of the turbine’s life cycle separately (materials acquisition, manufacturing, transportation, installation, operation and maintenance, and end of life) and multiple impact categories (environmental, human health, resource consumption). Particular attention was given to make the installation and maintenance phases complete and transparent. The contribution of this study is that it is the first comprehensive LCA for large wind turbines in the US, where different transport distances (including overseas transport of turbine parts), truck emission standards, mixes of electricity sources, and waste disposal practices will affect impacts, compared to those conducted for other countries. It is also the first comprehensive LCA to examine separately all 6 phases of the turbine’s life cycle (in particular separating manufacturing from raw material acquisition/installation) and the first to evaluate turbine lifespan as a sensitivity parameter. The study was conducted for 200 Gamesa 2-MW wind turbines located near Abilene, Texas. SimaPro8 software was used for modeling, according to ISO 14040 standards. The manufacturing phase contributed the greatest overall impacts, which was consistent with other studies; hence, alternative methods of manufacturing should be explored to reduce impacts. Installation, transportation, maintenance, and raw materials acquisition ranked second through fifth, respectively. Consistent with other studies, end-of-life ranked last, which means that the disposal method (landfilling or combustion) for turbine parts which are not recycled makes little difference in terms of the overall turbine life cycle.