USS Reefer, was a pilot schooner purchased by the United States Navy at New York City on May 25, 1846 from shipbuilders Brown & Bell for service as a dispatch boat in Commodore David Conner's Home Squadron during the Mexican–American War.

Early in August, she participated in an expedition against Alvarado, a river port some 30 miles from Veracruz, which sheltered a number of Mexican gunboats.

On October 16, 1846, Reefer got underway with a task force commanded by Commodore Matthew C. Perry, but, on the 17th, she was separated from her consorts in a severe storm and missed participating in the expedition up the Tabasco River.

Alvarado and Tuxpan fell in April, and in June Frontera and Tabasco came into American hands ending the fighting on the Mexican east coast.

Thereafter, Reefer and her sister ships settled down to blockade duty and maintained both water lines of supply and communication for the Army.