Rhode Island (USA) is 15 times larger than Washington, D.C..
Rhode Island, officially the State of Rhode Island and Providence Plantations, is a state in the New England region of the United States. Rhode Island is the smallest in area, the eighth least populous, but the second most densely populated of the 50 US states behind New Jersey. Wikipedia
Area: 178 km2 calculated
Washington, D.C., formally the District of Columbia and commonly referred to as Washington, "the District", or simply D.C., is the capital of the United States. Wikipedia