The United States Cavalry, or U.S. Cavalry, was the designation of the mounted force of the United States Army from the late 18th to the early 20th century. The Cavalry branch became the Armor branch in 1950, but the term "Cavalry" remains in use in the U.S. Army for mounted (ground and aviation) reconnaissance, security, and target acquisition (RSTA) units based on their parent Combat Arms Regimental System (CARS) regiment. Cavalry is also used in the name of the 1st Cavalry Division for heraldic/lineage/historical purposes.