May Day from Writers Almanac compiler Garrison Keillor's viewpoint

Today is May Day, the first of May, a date that may have more holidays than any other. It's the date when many countries celebrate Labor Day, a tradition with its roots in the 19th-century labor movement in the United States. In 1886, unions around the country went on strike in support of an eight-hour workday. Since many of the organizers of the strikes were communists, socialists, and anarchists, May Day has also come to be associated with communism, and was a big national holiday in the Soviet Union. President Eisenhower tried to take back May Day during the Cold War by declaring it Law Day and Loyalty Day. It remains a day of rallies and protests in many parts of the world, and in 2006, protest returned to the United States on May 1st to call attention to immigrants' rights.
Its roots as a holiday run much deeper than the labor movement, however. It's been a celebration of spring and fertility in places like Egypt and India, and in pre-Christian Rome it was the time of the festival of Flora, the goddess of flowers. In medieval England, people gathered flowers to "bring in the May" and erected a maypole bedecked with garlands. It's also the date of Beltane, a Celtic calendar festival celebrating the start of summer. Beltane was known for its bonfires, and has been revived by neo-pagans all over the world as a major religious holiday. In Germany, May 1st was the date of a pagan festival that was assimilated by the Christians and turned into the feast day of St. Walpurgis. The night before — Walpurgisnacht — is still celebrated in parts of rural Germany as a kind of Valentine's Day, with the delivery of a tree, wrapped in streamers, to one's beloved. It's also a day to celebrate Hawaiian history and culture, and it's known as Lei Day in Hawaii. One of the largest contemporary May Day celebrations in the United States takes place in Minneapolis, with a parade and pageant staged by the Heart of the Beast Puppet Theatre. It's been going on since 1975 and attracts about 35,000 people every year.
http://writersalmanac.org/