The second USS Union was a schooner that served in the United States Navy briefly during the Mexican War. Union was serving as a Mexican schooner when the U.S. Navy steam screw corvette USS Princeton captured her off Tampico, Mexico, on 14 November 1846. She entered U.S. Navy service later that month with Lieutenant John Ancrum Winslow in command. Poorly equipped, Union was wrecked on a reef off Veracruz, Mexico, on 16 December 1846.