USA callsign numbers mean little these days.
At one time you could be sure where a station was located in the USA by his number. W4 for example was Florida or nearby and W6 California or nearby. KF1BUZ is monitoring 10m JT65 but he is located in Nevada! A W6 could be in New England now!
I blame it on the FCC. Whoever thought up the present scheme needs his/her head relocating to a different call area. As someone located in Europe, the present system is poor.