Darling served as federal collector of internal revenue for the ninth district of New York from April 26, 1869, to April 17, 1871, and as a federal customs appraiser from April 18, 1871, to April 1, 1876.
Darling held various administrative positions in the U.S. government, specifically as federal revenue collector for New York's ninth district from April 26, 1869, to April 17, 1871, and as a customs official from April 18, 1871, to April 1, 1876.