In the twenty-three years between 1945 and 1968, under the old convention system, only a single outsider (Dwight Eisenhower) publicly sought the nomination of either party. By contrast, during the first two decades of the primary system, 1972 to 1992, eight outsiders ran (five Democrats and three Republicans), an average of 1.25 per election; and between 1996 and 2016, eighteen outsiders competed in one of the two parties’ primaries—an average of three per election. Thirteen of these were Republicans.
