Groundhog Day may be associated with the 1993 Bill Murray film, but its origins lie with German settlers in the 18th century.
The name Punxsutawney, the town in Pennsylvania where the groundhog ceremony takes place every year, comes from the Indian name for the location "ponksad-uteney", which means "the town of the sandflies".
When German settlers arrived in the 1700s, they brought the celebration of Candlemas with them. German tradition holds that if the sun comes out on Candlemas, the hedgehog will see its shadow and six more weeks of winter will follow. If no shadow is seen, legend says spring will come early.
The German settles in Pennsylvania continued the tradition but used a groundhog rather than a hedgehog.
The first official Groundhog day was on February 2, 1887, at Gobbler's Knob, about 65 miles northeast of Pittsburgh, although its first reference can be found in 1841.
Today it is celebrated in the US and Canada, with the most popular ceremony in Punxsutawney, although there are several others across both countries. Crowds in Punxsutawney can be as large as 40,000, and have increased in popularity since the Bill Murray film.
Punxsutawney Phil, the world's most famous groundhog, has seen his shadow nearly 100 times, has not seen it 15 times, and nine years are unaccounted for - but it should be said he only has an accuracy rating of 39 per cent.
The commercially and critically successful 1993 Murray film is about Phil Connors, an arrogant weather man sent to cover the Punxsutawney ceremony. He subsequently lives groundhog day repeatedly until he gets the day "right". In 2006, the film was added to the United States National Film Registry as being deemed "culturally, historically, or aesthetically significant." -1:00PM GMT 02 Feb 2011