One of the reoccurring themes in international relations scholarship over the last fifty years has been the idea that the United States has undergone a decline. The United States established itself as a hegemon in the years following World War 2 thanks to a preeminence in power. However, it has been argued that the hegemony of the United States may now be at risk and that the American power advantage is shrinking in the face of rising challengers. This thesis examines American decline through an extensive literature review followed by an analysis of fifteen metrics of power capabilities along with three indicators of the liberal hegemonic order which the United States is trying to maintain. The results of this analysis demonstrate that the United States has undergone a relative decline in state power capabilities in recent years which has destabilized the American led liberal hegemonic order.