Just south of Interstate 10 off Rancho Avenue, it’s impossible to miss Slover Mountain. An American flag sits firmly planted atop the limestone hill, home to the California Portland (Cal Portland) Cement Company.

Slover Mountain was named after Isaac Slover, a hunter and fur trapper who was killed by a bear in the Cajon Pass in 1854. He settled on the south slope of the mountain in 1841 or 1842 and built a cabin.

American Indians who inhabited the area long before Slover called the limestone wonder “Tahualtapa” or “The Hill of the Ravens,” and the Spaniards called it “Cerrito Solo,” meaning “The Little Hill That Stands Alone,” according to a Cal Portland news release.

It was later learned that marble could be quarried from the mountain, but the marble was exhausted by 1887.

Since Cal Portland started extracting limestone from the mountain to manufacture cement in 1894, the hill has been steadily dwindling in scale.

Former cement plant manager Thomas Fleming was responsible for the flag that has fluttered atop the hill since 1917.

“The story goes, he went to the Chicago World’s Fair, saw the flag there when they unfurled it at night with lights and everything,” said Gary Thornberry cq, Cal Portland’s environmental plant services manager. “And so he came back here and said he wanted to put a flag on the mountain.”

After receiving Congressional approval, the 30-foot by 20-foot flag was raised July 4, 1917. The next day, a headline in the San Bernardino Sun read: “Unfurling of Colton’s Liberty Flag is a Wondrous Spectacle.”

At the time, Mount Slover was one of only three locales in the United States where Old Glory flew around the clock. The other two locations were the White House and the gravesite of Francis Scott Key, who wrote the Star Spangled Banner, Thornberry said.

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