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.

For more help, see section 17j.