The Chincoteague Island Pony Festival has been documented as far back as the early 1800s. The event was described in 1835:
The rustic splendor, the crowd, and wild festivity of the horse-pennings, scarcely retain a shadow of their ancient glory. The multitudes of both sexes that formerly attended those occasions of festal mirth, were astonishing. The adjoining islands were literally emptied of their simple and frolic loving inhabitants, and the peninsula itself contributed to swell the crowd, for fifty miles above and below the point of meeting. All of the beauty and fashion of a certain order of the female population, who had funds, or favorites to a command passage, were sure to be there.
Legend says that the first swim was from the shipwreck of La Galga in 1750
It seems that the festival may have waned in the late 1800s as it was revived in 1925 by the Chincoteague Volunteer Fire Department which became their primary source of operating funds. As many as 50,000 tourists come each year to seen the horses make the historic swim across the channel which separates Assateague from Chincoteague Island travelling from all over the United States and Canada and even abroad.
The ponies are rounded up and penned on Assateague leading up to the festival which happens every year during the last week of July. The horses are swum on Wednesday and then paraded through town to the festival grounds. On Thursday, the pony auction is held and then Friday, the remaining herd is swum back to Assateague.