Trooper W.C. Wheeler of the state Highway Patrol said the collision occurred shortly after 6:30 a.m.
He said Hilda Arp was standing on the center yellow highway line at the time she was struck. A southbound vehicle swerved and missed her but a northbound vehicle struck her.
It was not clear why she was standing in the roadway.
No charges will be filed against the driver who struck her, the trooper said.