"Marsh Tacky" horses were used to manage cattle and to chase wild hogs. © Phil Sponenberg
The breed is descended from the original Spanish horses brought across the Atlantic in the 1500s and 1600s.
They are considered a level-headed breed that stands between 1.2m and 1.5. tall, with a compact body. They are named for their ability to move through marsh bogs without getting stuck.
The Republican state bill, being promoted by Catherine Ceips, who represents Beaufort, is aimed at lifting the profile of the breed, with fewer than 200 purebred examples said to be left in South Carolina.
Supporters of the breed ultimately hope to create a stud book, define the breed, and find some fresh Marsh Tacky bloodlines to be introduced to the gene pool.
The breed is said to have been crucial in the area during the American Revolution, allowing Revolutionary commander Francis Marion and his men to evade British troops through swampy terrain.