History
Horseshoe pitching probably grew out of quoits, a game played by Roman soldiers in the early Christian Era, in which a ring is tossed at a stake or pin set in the ground. (The indoor children's game commonly known as "ring toss" is a scaled down version.)
Some writers think it happened the other way around: that horseshoe pitching came first and quoits followed. Others say that quoits was played by the Roman officers, while the common foot soldiers had to content themselves with using horseshoes. The problem with both of those theories is that there's no evidence that the Romans used U-shaped horseshoes. In fact, Roman horseshoes were either solid plates or closed rings, similar to quoits, and they were fastened by straps, not nailed onto the hoof.
It seems very likely that the Romans did introduce quoits during their occupation of Britain, from the 1st to 5th century, and that English picked up the game from them.
Quoits became popular enough in England that it was banned twice in the late 14th century. At some point—no one knows exactly when—horseshoe pitching sprang up as a form of quoits ready-made for peasants. (One theory is that, originally, horseshoes were bent into quoits rings and, eventually, someone decided that was just too much work and began to play with an unaltered horseshoe.)
In any event, both quoits and horseshoe pitching were brought to America by English settlers. During the 19th century, quoits was more popular in the Eastern United States, while horseshoe pitching was more popular in the Midwest. During the Civil War, Union soldiers whiled away time by pitching mule shoes on improvised courts set up in their camps, and many of them undoubtedly introduced the game to others after the war.
The first horseshoe pitching club was organized in Meadville, Pennsylvania, in 1899. Unfortunately, little is known about it. In 1909, a "world championship tournament" was held in Bronson, Kansas. The first known written rules come from that tournament. The stakes extended only 2 inches above ground level and were 38 feet apart. Ringers counted 5 points, leaners 3 points, and other scoring shoes 1 point each, with the winner being the first competitor to score 21 points.
The Grand League of the American Horseshoe Pitchers Association (GLAHPA) was founded in Kansas City, Kansas, on May 6, 1914. Under its rules, the stake was 8 inches high; the pitcher's box was a 6-foot square, and the allowable weight of the horseshoe was set at between 2 pounds and 2 pounds, 2 ounces. The distance between stakes was still 38 feet and the scoring rules were the same as in the 1909 tournament, except that a shoe had to be within 6 inches of the stake to count.
In 1919, the distance between stakes was increased to 40 feet and game was raised to 50 points. The following year, the height of the stake was raised to 10 inches and the diameter increased from 3/4 inch to 1 inch. Leaners were eliminated from scoring, except as close shoes counting 1 point each.
A second organization, the National League of Horseshoe and Quoit Pitchers (NLHQP), had been founded in St. Petersburg, Florida, on February 26, 1919. It looks as if there was a race to get control of the sport, because both organizations were incorporated in Ohio in 1921. They merged as the National Horseshoe Pitchers Association of America in 1925. It's now known simply as the National Horseshoe Pitchers Association (NHPA).
Only two important rules changes have been made since then. The height of the stake was raised to 14-15 inches in 1950 and the number of points required to win a game was changed to 40 in 1982.
Like several others sports, including badminton, croquet, and table tennis, horseshoe pitching is very popular as a recreation but not as a serious competitive sport. The NHPA estimates that more than 15 million people play the sport at least once in the course of a year, but association membership is only about 15,000.