Founded in 1959, this association boasts over 15,000 worldwide members and hosts over 260 events a year. United States Eventing Association, or USEA, is a resource for equestrian education, safety, horse welfare, certification, training and information for its members. An extensive library is housed in the Leesburg office located across from Morven Park. USEA strives to be the leader in making eventing competition more user-friendly, enjoyable, efficient, simpler and affordable.