During his tenure, McCreary represented Kentucky's agricultural interests, introducing a bill to create the United States Department of Agriculture. A bill containing most of the same provisions as the one McCreary authored was passed later in the session. He also proposed a successful amendment to the Wilson–Gorman Tariff Act that excluded farm implements and machinery from the tariff. An advocate of free silver, he was appointed by President Benjamin Harrison to be a delegate to the International Monetary Conference held in Brussels, Belgium, in 1892. As chairman of the House Committee on Foreign Affairs, he authored a bill to establish a court that would settle disputed land claims stemming from the Gadsden Purchase and the Treaty of Guadalupe-Hidalgo. He advocated the creation of a railroad linking Canada, the United States, and Mexico. In 1890, he sponsored a bill authorizing the first Pan-American Conference and was an advocate of the Pan-American Medical Conference that met in Washington, D.C., in 1893. He authored a report declaring American hostility to European ownership of a canal connecting the Atlantic and Pacific Oceans, and sponsored legislation authorizing the U.S. president to retaliate against foreign vessels that harassed American fishing boats.