Stubborn and silly or smart and courageous - depending on your point of view
The donkey has become the established political symbol for the Democratic Party, although it has never been officially adopted.
Like many traditions however its origins have been clouded by the passage of time.
Most records seem to agree that - as with the elephant used by the Republicans - the 19th century political cartoonist Thomas Nast, had much to do with the donkey's popularisation.
However, according to Democratic Party historians the earliest example of the donkey coming into political use was during Andrew Jackson's campaign for the presidency in 1828.
At the time, Jackson's opponents labelled him a "jackass", apparently for his populist views and his slogan, "Let the people rule."
President Jackson adopted the donkey as his own symbol
Not to be outdone Jackson himself adopted the donkey symbol for his campaign posters - an image that stuck with him during his presidency as a result of his stubborn reputation.
After Jackson retired in 1837 he was still widely regarded as a party leader, even though the party - like a stubborn donkey - refused to be led. An 1837 cartoon entitled "A Modern Baalim and his Ass" showed him leading a donkey which refused to follow.
It was to be another three decades however before Thomas Nast's cartoons helped cement the donkey as the popular symbol of the Democratic Party.
The animal first appeared in an 1870 Harper's Weekly cartoon, labelled as the "Copperhead Press" and kicking a dead lion symbolising Lincoln's Secretary of War, Edwin M. Stanton, who had recently died.
Thomas Nast's cartoons helped establish the donkey as the Democratic symbol
The donkey was used to represent a group of northern anti-civil war Democrats with whom Nast disagreed - but the symbol caught the popular imagination and he continued to use it to represent pro-Democrat editors and newspapers.
By the 1880 presidential campaign the donkey had become firmly established as a political symbol.
A cartoon in the now defunct New York Daily Graphic at the time showed the losing Democrat candidate, Winfield S. Hancock leading a team of party crusaders into battle on the back of a donkey.
Critics of the party regard the symbol as stubborn, silly and ridiculous. Die-hard Democrats however say the animal represents the humble, homely, smart, courageous and loveable aspects of the party.