Rock Mary, in Caddo County, Oklahoma, was a prominent landmark on the California Road.

Mary was the eldest daughter of Dr. John R. Conway, a prominent physician and surveyor, who emigrated to California with his wife and 10 children.

Harrison when they visited this site, planted a flag on the crest and named the rock for 17 year belle, Mary Conway, an emigrant.

By this act they established this as a famous landmark relied on by countless thousands of western emigrants.

The Hinton Historical Museum has been granted access management of the property and can allow visitors to enter with advance notice.