High Quality Content by WIKIPEDIA articles! The Little Miami River is a Class I tributary of the Ohio River that flows 105.5 miles through five counties in southwestern Ohio in the United States. The Little Miami joins the Ohio River east of Cincinnati. It forms parts of the borders between Hamilton and Clermont Counties and between Hamilton and Warren Counties. The National Wild and Scenic River lends its name to the Little Miami Scenic Trail. The Little Miami River is a tributary of the Ohio River. It is part of a watershed that drains a 1,757 square miles area in 11 southwestern Ohio counties: Clark, Montgomery, Madison, Greene, Warren, Butler, Clinton, Clermont, Brown, and Highland.