She transported the Haitian Commission to Santiago, Cuba, arriving 14 March 1930, then visited New York and Chesapeake Bay for the Presidential Fleet Review of 19 May before returning to the west coast in June.

She escorted President F. D. Roosevelt in Potomac to New Orleans and Texas, then served in Midshipman and Naval Reserve training cruises and on Neutrality patrol along the eastern seaboard to Cuba until September 1941.

Decatur joined the task group centered about USS Card and sailed from Norfolk 24 November 1943 for an antisubmarine sweep, returning to New York 3 January 1944.

On the last day of March while sailing between Oran and Algiers, the force successfully repelled a coordinated strike of German submarines and planes, to arrive at its destination 3 April.

Arriving at Norfolk 2 July 1944 Decatur sailed from this port on escort and training duty in the Caribbean Sea until the last day of June 1945 when she entered Philadelphia Naval Shipyard for inactivation.