Aggregate party identification (macropartisanship) has exhibited substantial movement in the U.S. electorate over the last half century. We contend that a major key to that movement is a rare, massive, and enduring shift of the electoral equilibrium commonly known as a partisan realignment. The research, which is based on time-series data that employ the classic measurement of party identification, shows that the 1980 election triggered a systematic growth of Republican identification that cut deeply into the overwhelming Democratic lead dating back to the New Deal realignment. Although short-term fluctuations in macropartisanship are responsive to the elements of everyday politics, neither presidential approval nor consumer sentiment is found responsible for the 1980 shift.