User blog comment:SonOfZeus1200/The Camp Half-Blood & Kane Chronicles Series will collide!/@comment-2212711-20120815004846/@comment-3146930-20120815005629

I think they mention the unexplained magic was around Long Island, not NYC. However, the Kane series makes several mentions of characters trying to avoid New York City. As far as what year the books happen in comparison to the PJO series, I'm not sure as I'm not an expert on that series.