Haines defeated Martha Lang, 2 and 1, while Creekmore posted a 2-up victory over Toni Wiesner to set up their showdown in the final.
Earlier in the day, Haines won her quarterfinal match with Marianne Towersey, 3 and 2, and Creekmore blasted Ann Lahey, 7 and 6, to advance.
'I am playing better than ever,' said Creekmore, 'This is so exciting I can't even tell you. I just know I'm going to get to play tomorrow.'
The final round will be an 18-hole match that will take place on Thursday.
The Senior Women's Amateur is one of 13 national championships conducted annually by the United States Golf Association, 10 of which are strictly for amateurs.