The Gemara considers the Atlantic as the end of West, so obviously, we are at the extreme east. Therefore, it is Shabbos here while it is Thursday midnight in Eretz Yisroel.
Also, according Rashi in the name of the Tachkmoni, the sun was created in the fourth hour of the night. At that time it was night in Eretz Yisroel and day in America. Which day was that? If it was Tuesday, then the Meoros were put a day early, so it must have been the next day. Hence, we are a day ahead, in stead of behind.