Twins Days is held annually on the first full weekend in August in Twinsburg, Ohio, United States to celebrate biological twins (and other multiples, e.g. triplets, quads). It is the largest annual gathering of twins in the world, and draws thousands of participants from all over the United States and elsewhere in the world.
It was founded in 1819 by identical twin brothers, Moses and Aaron Wilcox. The town of Twinsburg, with a population of just under 20,000, has since set aside a few days each year to celebrate the "uniqueness" of twins and multiples. To date, it has attracted more than 80,000 sibling groups to participate.
The event typically attracts around 2,000 twins including those from Nigeria, Brazil, Australia, Ghana, Canada, Ireland, New Zealand, France, Italy, UK, Belgium, Germany, Japan, China and India, and more. For three days, pairs of identical twins, dressed the same, roam around the town to gather and bond over their twin-ness.
The highlight of the festival is arguably the Double Take Parade. It draws hundreds of spectators, who set up their lawn chairs along each side of Ravenna Road, the town's main strip, to watch a sea of twins march through the city. Furthermore, the event features contests including awards for the twins who travelled the longest distance to attend.
The event is also a magnet for researchers — a potential treasure trove of human data for scientific study. The festival offers a unique scientific opportunity for researchers to gather subjects with identical DNA in order to learn whether certain conditions are influenced by genetics or environmental factors. Researchers set up tents on the festival grounds, where twins can volunteer to be tested.
Most importantly, this is certainly a unique opportunity for twins and multiples to meet, take pictures with other twin sets, swap fun twin stories, and bond.
According to cbc.ca & Wikipedia