The Narragansett Pacer was one of the first recorded horse breeds developed in the United States. It emerged in the 1700s, and is believed to have been bred from a mix of English and Spanish breeds. The Pacer was associated with Rhode Island. The last known Pacer is thought to have died around 1880. The Pacer was known as a sure-footed, dependable breed, although not flashy or always good-looking. Pacers were used for racing and general riding. They provided the foundation for several other American breeds.

The Narragansett Pacer was not exclusively a pacing horse, as evidence indicates that it exhibited an ambling gait. The amble is more comfortable to ride than the pace gait, and Narragansett Pacers were known for their qualities as riding and driving horses. They averaged around 14.1 hands (57 inches, 145 cm) tall, and were generally chestnut in color. James Fenimore Cooper described their conformation as such: "They have handsome foreheads, the head clean, the neck long, the arms and legs thin and tapered."

Dutson states: "They are very spirited, and carry both the head and tail high. But what is more remarkable is that they amble with more speed than most horses trot, so that it is difficult to put some of them upon a gallop." Other viewers of the breed rarely called them stylish or good-looking, although they considered them dependable, easy to work with, and sure-footed.

The Narragansett Pacer had a major influence on many American gaited horse breeds. It was especially associated with the state of Rhode Island in the early 18th century (1700s), but became extinct by the late 19th century. It was known as one of the first breeds of horse developed in America. The origin of the breed is unknown, but it was probably developed from a cross between English "ambling" horses and Spanish breeds. The horses developed from this cross were known for their smoothness and sure-footedness over poor terrain.

The English horses which contributed to the Narragansett Pacer may have been members of the Irish Hobby breed; another possible ancestor is the Galloway pony.

In the early 1700s, Rhode Island Lieutenant Governor William Robinson began the serious development of Narragansett Pacer breed with a stallion named "Old Snip", speculated to be either an Irish Hobby or an Andalusian (Iberian horse), and considered to be the father of the breed.

In 1768, George Washington owned and raced a Narragansett Pacer, and Edmund Burke asked an American friend for a pair in 1772. Paul Revere possibly rode a Pacer during his 1775 ride to warn the Americans of the British attack. Scots-Irish judge and Patriot sympathizer George Grant McCurdy of Old Lyme, Connecticut also owned a Narragansett Pacer mare. The Narragansett Pacer would prove to be immensely popular in the 18th century, and dominated early horse races in Colonial America.

The extinction of the Narragansett Pacer as a breed was thought to be mainly due to two factors. The first of these factors was the introduction of the English Thoroughbred to the United States from England.

The Thoroughbred also supplanted the Narragansett Pacer as the favored horse breed of the United States Cavalry. The disappearance of the Narragansett Pacer through heavy crossbreeding to Thoroughbreds, particularly for refined cavalry and racing horses, was also noted by Confederate General Basil W. Duke in his 1911 memoir Reminiscences of General Basil W. Duke, C. S. A.

Duke also credits the rise of "larger stakes and purses offered, and the breeding of the Thoroughbred becoming a profitable industry...[along with] 'match races', in which two famous racers would be pitted against each other" with the demise of the Narragansett Pacer. He also notes that "wealthy farmers...were the principal patrons of the sport", and chose Thoroughbreds over Pacers for their popularity and speed, as well as greater winnings.

The second factor in the breed's extinction was that Pacers were sold in large numbers to sugarcane planters in the Caribbean, as well as buyers in Canada, to purchase Thoroughbreds instead, thereby severely diminishing the purebred stock in the United States. The few horses that were left were crossbred with the Thoroughbred to create and improve other breeds, including the Morgan and the Standardbred. Due to this, the pure strain of the Narragansett Pacer eventually became extinct sometime in the 1800s.

North Carolina also had breeders of the Pacer, as the breeding stock was brought to the area around 1790 by pioneers, though Duke notes that Virginia Thoroughbreds were later highly sought-after. The last known purebred Pacer is thought to have died around 1880, though this is disputed by other sources. As no formal breed registry or studbook was created to record Narragansett Pacer horses, identifying them is done through cross-referencing historical documents, as well as instances of crossbreeding in early pedigrees.

The breed was used for "pacing races" in Rhode Island, where the Baptist population allowed races when the greater part of Puritan New England did not. Pacers reportedly covered the one-mile tracks in a little more than two minutes.

The Narragansett Pacer played a significant role in the creation of the Morgan, American Saddlebred, the Standardbred, and the Tennessee Walking Horse. The breed was also combined with French pacers to create the Canadian Pacer, a breed especially suited to racing over ice, and which also contributed substantially to the creation of the Standardbred.

In the early 19th century, Pacer mares were bred to stallions of the fledgling Morgan breed. However, the Morgan breed was selected for a trot as an intermediate gait, and thus ambling horses were frowned upon, so most gaited Narragansett/Morgan crosses were sold to Canada, the Caribbean, and South America, so the bloodlines did not remain within the Morgan breed. Other breeds indirectly influenced by the Narragansett Pacer include the Rocky Mountain Horse, a gaited breed started in Kentucky; the Tiger Horse, a gaited breed with leopard complex patterning, and more.

The Narragansett Pacer also served as foundation stock for the Canadian horse. In 1896, Leonard D. Sale wrote in The Horse Review of Chicago that an Assateague resident imported and released a "Canadian-bred pony stallion" in an effort to improve the Chincoteague Pony breed of Virginia. The resulting foals from the Canadian pony sire were also gaited, indicating the sire may have had Narragansett Pacer genes: "A few island ponies pace, but they carry an infusion of the Canadian scrub blood."

The Narragansett Pacer also influenced the Paso Fino and other non-American gaited horse breeds. Per the International Museum of the Horse, "The Paso Fino is a direct descendant of the Narragansett Pacer, and is probably almost the same horse." However, a 2022 genetic study showed that the Paso Fino likely descended from not only Narragansett Pacers, but various other Spanish and Iberian horse breeds, such as the Andalusian and Lusitano; also related were the Morgan and the Florida Cracker Horse.

• Facsimile edition of Dodge, T. A. (1892). "The Horse in America". North American Review, vol. CLV, pp. 667-683.
• Facsimile edition of Earle, A. M. (1890). "Narragansett Pacers". New England Magazine, vol. II March-August, pp. 39-42.
• Facsimile edition of Updike, W. (1847). "History of the Church in Narragansett". United States Magazine, and Democratic Review, vol. XXI, pp. 347-353.