Yellow Dog Democrats was a political term applied to voters in the Southern United States who voted solely for candidates who represented the Democratic Party. The term originated in the late 19th century. These voters would allegedly "vote for a yellow dog before they would vote for any Republican". The term is now more generally applied to refer to any Democrat who will vote a straight party ticket under any circumstances. The South Carolina Democratic Party and Mississippi Democratic Party, among other state parties, continue to use the phrase to refer to committed members of the Democratic Party in the "Yellow Dog Club."
The phrase "yellow dog" may be a reference to a breed of dog known as the Carolina Dog indigenous to the Americas, specifically the Southern United States, and not descended from Eurasian breeds.
The phrase "Yellow Dog Democrat" is thought to have achieved popularity during the 1928 presidential race between Democratic candidate Al Smith and Republican candidate Herbert Hoover, when Senator J. Thomas Heflin (D-Alabama) crossed party lines and formally supported Hoover. Many Southern voters disliked several items on Smith's platform but still voted for him.
The term was also used by Abraham Lincoln in an 1848 speech on the presidential campaign of General Zachary Taylor, whose Democratic opponent was General Lewis Cass. Lincoln derided Cass as one of several recent Democratic presidential candidates in the mold of Andrew Jackson by saying:
"A fellow once advertised that he had made a discovery by which he could make a new man out of an old one, and have enough of the stuff left to make a little yellow dog. Just such a discovery has Gen. Jackson's popularity been to you [Democrats]. You not only twice made President of him out of it, but you have had enough of the stuff left to make Presidents of several comparatively small men since; and it is your chief reliance now to make still another."