It rises in the Appalachian Mountains of southwestern Virginia, in eastern Buchanan County, near Grundy.

It flows west into Pike County, Kentucky, where it is impounded to form Fishtrap Lake reservoir.

It joins the Tug Fork from the southwest at Louisa on the West Virginia state line to form the Big Sandy.

[2] According to Robert F. Collins of the United States Forest Service, 18th-century explorer Dr. Thomas Walker had named the nearby Kentucky River the Louisa River, after Princess Louisa, sister of Prince William Augustus, Duke of Cumberland (Walker had just named the Cumberland River a month or two earlier).

According to George R. Stewart, frontiersmen "forgot" who it was named for and it changed over time to Levisa.