The United States Cavalry, or U.S. Cavalry, was the designation of the mounted force of the United States Army by an act of Congress on 3 August 1861. This act converted the U.S. Army's two regiments of dragoons, one regiment of mounted riflemen, and two regiments of cavalry into one branch of service. The cavalry branch transitioned to the Armored Forces with tanks in 1940, but the term "cavalry", e.g. "armored cavalry", remains in use in the U.S. Army for mounted (ground and aviation) reconnaissance, surveillance, 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. Some combined arms battalions (i.e., consisting of a combination of tank and mechanized infantry companies) are designated as "armor" formations, while others are designated as "infantry" organizations. These "branch" designations are again, heraldic/lineage/historical titles derived from the CARS regiments to which the battalions are assigned.