Yohogania is West Virginia's phantom county, created in the same legislative act with Monongalia and Ohio counties but later lost to history. The county arose in the early border dispute between Virginia and Pennsylvania over lands now in north-central West Virginia and the Northern Panhandle and in the adjacent southwest corner of Pennsylvania. Most of Yohogania County fell within present Pennsylvania, but its territory also included what is today Hancock County, West Virginia.

After settlers began to move into the frontier area, there was a need for local government. Disregarding Pennsylvania's claim to the land, Virginia organized the territory into the District of West Augusta. During the American Revolution, Virginia divided West Augusta into three counties, Ohio, Yohogania, and Monongalia. Early maps show that Yohogania County encompassed territory north of the present West Virginia-Pennsylvania state line and primarily east of the Allegheny River, while Monongalia County then covered much of what is now north-central West Virginia plus most of present Greene, Fayette, and Washington counties in Pennsylvania. Ohio County got most of the present panhandle and lands to the south, as well as a sliver of present Pennsylvania.

Virginia and Pennsylvania continued to dispute this territory until an agreement was reached in 1780 to extend the Mason-Dixon Line between the two states. Yohogania County quickly ceased to exist as other counties were carved from its territory. They included Fayette, Allegheny, Westmoreland, Washington, and Greene counties in Pennsylvania, and the northern tip of Ohio County (now Hancock). Ohio and Monongalia counties, covering nearly all of northwestern Virginia, themselves later contributed territory to nearly a dozen counties of present West Virginia.