Nearly all the K's east of the Mississippi (like KYW and KDKA) and nearly all the W's west of the Mississippi (WBAP, WOW, WFAA, WDAF, WNAX) were grandfathered calls from the 1920s. Very early on, in 1920-22 when the pioneering handful of stations was licensed, there weren't hard and fast geographic rules about callsigns. When the first rules were put in around 1922-23, after several hundred stations had been granted construction permits by the Commerce Department, the K/W dividing line was a couple hundred miles further west beyond the Mississippi River, close to the geographic centerline of the continental United States. It was only later on in the 1920s, as the Federal Radio Commission started its work, that the river became the K/W line, after dozens of nonconforming callsigns had been assigned. No one already licensed was forced to change. There were a few metro areas straddling the river (Minneapolis/St. Paul, St. Louis) that have had a mix of K and W callsigns from the start, while New Orleans and Baton Rouge seem to have nearly all W calls even though they, too, straddle the river.
When you get a K callsign east of the Mississippi now, like this one on Long Island and another one licensed a few years ago in northern Michigan, it's a bureaucratic screw-up. But again, once a callsign gets assigned, if the licensee is OK with it and it doesn't have an insulting or obscene connotation in any language, they can keep it even if it's an error.
