There is no evidence to suggest that St. Patrick's Day is celebrated with green beer. The tradition of associating green beer with St. Patrick's Day is a relatively modern one, likely dating back to the early 20th century. It is believed to have originated in the United States, where pubs used food coloring to make their beer appear festive. The tradition has since spread to many other countries, but it is still primarily associated with St. Patrick's Day celebrations in the United States.