<human>:  What is the history behind the holiday of Groundhog Day?
<bot>: Groundhog Day is a popular holiday celebrated in the United States and Canada on February 2. The holiday is based on a Pennsylvania Dutch superstition which states that if a groundhog emerges from its burrow on this day and sees its shadow due to clear weather, winter will last for another six weeks. If, however, the day is cloudy, the groundhog will not see its shadow and the weather will be warmer, signaling the arrival of spring. The celebration of the holiday is believed to have been established in the 18th century by the Pennsylvania Dutch, who brought the belief to the United States. It has become a popular tradition in both countries, with groundhog festivals held in several cities and towns throughout Canada and the United States. Today, modern-day predictions by groundhogs are made on the holiday.