USS Idaho (1864), a 3241-ton steam sloop, was part of an American Civil War program of large, very fast, steam cruisers. Completed in May 1866, she ran her sea trials the following August, making just over eight knots. Her boilers and engines, ordered as a result of political influence, failed totally to achieve her fifteen-knot contract speed. The U.S. Congress, however, stepped in and ordered its purchase. The ship was then modified with sail and became one of the fastest ships in the U.S. Navy.