Listen to people talk. The biggest feature in an area is THE feature. In Milwaukee, if you say The Lake, you mean enormous Lake Michigan, not some overgrown puddle surrounded by summer cottages. In Kansas City, The River is the wide Missouri, not the middle-sized Kansas River or the little Little Blue.

In this song, The Mountain is the big one in these parts, and there's no need to name it. I personally think that "she" is a famous entertainer on tour, such as Sarah Bernhardt or Jenny Lind.