Glendale was founded in 1862 by Mormon pioneers John and William Berry, abandoned in 1866 due to Indian attacks, and resettled in 1871.
In 1862 ranchers came to Long Valley, land east of Zion National Park, to graze cattle along the East Fork of the Virgin River. Robert and Isabella Berry named the area now known as Glendale, Berryville. In 1866 after the Berry’s were killed by Indians, the other settlers left.
It was in 1871 that Mormons, from the Muddy River settlement in Nevada, came to settle naming the town Glendale. The people of St. Thomas, Nevada relocated en masse to Glendale in this year, preserving the old ward organization at the new location. By the 1800s the Mormon communities in the area had grown in the nearby towns of Orderville and Mt Carmel Junction., Glendale became part of the United Order. The United Order movement was a program of economic and moral reform that began in 1874 under Brigham Young. On March 29, 1935 Glendale became an incorporated town. The Towns of Mount Carmel, Orderville, and Glendale are known as Long Valley.