Voting Statistics and Presidential Coattails

The coattail effect in presidential and congressional races was long supposed to show that the winning presidential candidate led his party to victory by adding votes to the ticket all along the line. The fact that the same party almost always won control of both houses of congress and usually also a majority of the governorships at stake at the time of a presidential victory made this a plausible theory.More recently, the sweeping nature of such an explanation has been challenged. The first criticism of the simple theory noted that even when a presidential candidate wins, congressional candidates in some districts lead the president. In these cases, presumably, the congressional candidates' coattails are more effective.A second criticism pointed to the paradox in the assumption that if a presidential candidate leads his party by a wide margin, he is an effective candidate for the party ticket. The greater the margin, presumably, the stronger are the presidential coattails. But large margins, on the contrary, must indicate that the presidential candidate has not been able to transfer all of his votes to the congressional ticket; and so it would seem that the attraction of his coattails is minimal if this margin is great. Thus the most significant symptom of the coattail process is straight ticket voting.