Numerical model studies have suggested that the ongoing global climate change will likely affect tropical cyclone activity. Since the global warming has been underway, it is meaningful to ask: Are there evidences of observed changes in tropical cyclone activity? Using best-track data from 1965 to 2003, we show for the first time that over the past four decades the two prevailing typhoon tracks in the western North Pacific (WNP) have shifted westward significantly; thus the subtropical East Asia has experienced increasing typhoon influence; but the typhoon influence over the South China Sea has considerably decreased. Our trajectory model simulation indicates that the long-term shifts in the typhoon tracks result primarily from the changes in the mean translation velocity of typhoons or the large-scale steering flow, which is associated with the westward expansion and strengthening of the WNP subtropical high.