What is the origin of the donkey and elephant as the symbols of the Democratic and Republican parties in America?
The Donkey— Presidential candidate Andrew Jackson was the first Democrat ever to be associated with the donkey symbol. His opponents during the election of 1828 tried to label him a "jackass" for his populist beliefs and slogan, "Let the people rule." Jackson was entertained by the notion and ended up using it to his advantage on his campaign posters.
But cartoonist Thomas Nast is credited with making the donkey the recognized symbol of the Democratic Party. It first appeared in a cartoon in Harper's Weekly in 1870, and was supposed to represent an anti-Civil War faction. But the public was immediately taken by it and by 1880 it had already become the unofficial symbol of the party.
The Elephant— Political cartoonist Thomas Nast was also responsible for the Republican Party elephant. In a cartoon that appeared in Harper's Weekly in 1874, Nast drew a donkey clothed in lion's skin, scaring away all the animals at the zoo. One of those animals, the elephant, was labeled "The Republican Vote." That's all it took for the elephant to become associated with the Republican Party.
—The Fact Monster