McCammon is well known for writing critically acclaimed horror novels in the 80s and early 90s. In fact, several of his award-winning books were the amazing post-apocalyptic novels, Stinger and Swan Song, to which The Border will inevitably be compared. But McCammon's more recent writing shows an expansion into much broader themes.
My introduction to McCammon's work was Boy's Life, a beautiful, gritty coming of age story of a boy trying to discover who killed a man that his father attempted to rescue, before the incident drives his father to insanity. The magic that dwells within the mind of every 12-year-old boy comes to life in this story, and it unfolds against the backdrop of racial inequality of the deep south (U.S.) of the 1960s. Wonderful story!
Perhaps the most stunning departure from McCammon's horror heritage is a series of historical mystery novels (with just a slight twist of the supernatural at times) about Matthew Corbett, a kind of self-made investigator in the late 17th century. The first book, Speaks the Nightbird, focuses primarily on a trial of a woman accused of witchcraft. I highly recommend the entire series.
And for one more major departure from his roots, in 2011 McCammon published The Five. This is a novel about a struggling, hard-working rock band on their last tour together. It is beautifully written (I would call it poetic) and is filled with subtle references to much of the same music I have listened to since I was a teen. It is McCammon's love letter to rock-n-roll, and I just wish I could have been the one to write it.
If you are a McCammon fan, great! If you haven't tried him yet, I hope this gives you ideas for which books might be most suitable as an introduction to his work.