The Yeocomico River is a 1.1-mile-long (1.8 km) tidal tributary of the southern portion of the Potomac River in Virginia's Northern Neck. The Yeocomico forms the boundary between Westmoreland and Northumberland counties. Yeocomico is a Native American name roughly translated as "tossed to and fro by the waters." Others suggest it is an Algonquian word that means "four dwelling places" since the river has a branch on either side with each dividing into two large forks.