In 1957 the Army set up the Combat Arms Regimental System (CARS). Under CARS the regiment would be a group of tactical units bearing the regimental name. Over one hundred and fifty historic regiments of cavalry, armor, infantry and artillery were preserved. The original line companies/batteries/troops of a regiment would be activated as the headquarters company/battery/troop of newly constituted battle group/battalion/squadron to preserve the lineal ties with the old regiment. Should a separate company-sized element be required the original company/battery/troop would be activated.

On 15 February 1957, five elements of the 4th Cavalry were activated.

• The 1st Squadron, 4th Cavalry descending from "A" Troop was activated in the 1st Infantry Division at Fort Riley Kansas.
• The 2nd Battle Group, 4th Cavalry (infantry) descending from "B" Troop was activated and assigned to the 1st Cavalry Division to serve along the Demilitarized Zone (DMZ) in Korea.
• The 3rd Squadron, 4th Cavalry descending from "C" Troop joined the 25th Infantry Division at Schofield Barracks Hawaii.
• The 4th Squadron, 4th Cavalry descending from "D" Troop was activated with the Army Reserve 102nd Infantry Division at Kansas City, Missouri.
• The 5th Squadron, 4th Cavalry descending from "E" Troop was activated with the Army Reserve 103rd Infantry Division at Ottumwa, Iowa.

During the 1960s Army requirements led to changes in the active elements of the 4th Cavalry. On 01 August 1963, with the transformation of the 1st Cavalry Division to an Airmobile Division, its 2nd Battle Group was reorganized and redesignated as the 2nd Squadron and assigned to the 4th Armored Division. On 15 March 1963, the 5th Squadron was inactivated. Its predecessor "E" Troop was activated on 03 December 1963 and assigned to the Army Reserve 205th Infantry Brigade at Madison, Wisconsin. On 31 December 1965 the 4th Squadron was inactivated.