The book takes place in and around the environs of Southeast Pennsylvania. The specific places are mentioned are Chester, Harrisburg, Ephrata and Germantown. All of the places are based on real life locations. The vampire's den, "Rivenden" is based on the famous 18th C. Manor in Germantown called Clivenden. The author lived in the area for twelve years and accurately describes the climate and locations, right down to Scrapple.
Ah Scrapple. The taste of authenticity. Love it. And thanks to whoever updated the page.