Loretta Lynn has paved the way for artists such as, Reba McEntire and Wynonna Judd.

The Darby River, a branch of the Delaware, flows by our house in the mountains.

A branch of the Delaware is a nonrestrictive appositive—it modifies the proper noun Darby River—so the phrase is correctly set off with commas. In the other sentence, the comma is incorrectly placed following such as.