This paper studies the use of emotion and reason in political discourse. Adopting computational-linguistics techniques to construct a validated text-based scale, we measure emotionality in 6 million speeches given in U.S. Congress over the years 1858-2014. Intuitively, emotionality spikes during times of war and is highest in speeches about patriotism. In the time series, emotionality was relatively low and stable in earlier years but increased significantly starting in the late 1970s. Across Congress Members, emotionality is higher for Democrats, for women, for ethnic/religious minorities, for the opposition party, and for members with ideologically extreme roll-call voting records.