KC1AWS (5308km) was again the first to spot my 500mW WSPR beacon today, at 1218z. He was first yesterday too. Since then, other USA stations are spotting me.
UPDATE 1752z: At the moment it looks like KB9AMG (6300km) was the last USA station to spot my 500mW WSPR beacon at 1706z at -17dB S/N. No other stateside station has spotted me since then. It is interesting that the report suggests 20mW would have been enough. Then the path just dies out within minutes.