Socialist candidate Norman Thomas in 1936 received 46% of his vote from New York
Dixiecrat Strom Thurmond gained 54.9% of his vote in the deep south states of South Carolina, Mississippi, Alabama, and Louisiana. He also gained 9% more of his total vote in Texas in 1948
T. Coleman Andrews of the States Rights party in 1956 gained about 39% of its vote in Virginia and about 17% in Tennessee.
1832 Anti-Masonic candidate William Wirt got 66% of his vote in Pennsylvania.
The Anti-Masonry movement was key to flipping a lot of rural counties in the Mid Atlantic to the Whigs that possibly would have been likely to side with the Jacksonians against the "elitist Whigs". They instead swept up a lot of support in PA, NY and even parts of New England like VT and then rolled into the Whigs and if memory serves me, provided a substantial base within the Whig Party that supported Harrison but I might be mistaken on that.
It is definitely something that could use a good deal more analysis especially in comparison to the talk in current times in the UK of voters going Labour>UKIP>Conservative. So the notion of a third party movement taking a group of voters from a major party and bridging them to the other major party, is presently in the news.
