Around 1860 Raleigh Gentry settled a mile south of the present location of Cleo. The first attempt to establish a community took place on March 11, 1880, when Thomas Riggs opened a post office initially called Viejo for Viejo Creek (now West Bear Creek), which flows west of the town. Postal and telegraph service was discontinued in May 1886 and transferred to Junction City (now Junction). The Viejo post office was reestablished on March 25, 1915, and John Simpson ran the postal business in his general store. In August 1920 Simpson sold the store and transferred the postmaster's duties to Sam L. Pearson. Pearson changed the name to Cleo, in honor of his niece Cleo Weston. Cleo was a supply point for campers, hunters, and fishermen in the 1920s and 1930s. During the Great Depression years the unemployed also came to Cleo to find work cutting cedar. The Bear Creek School in Cleo closed in 1937, but the building continued to be used for social events. The population of Cleo was reported as between fifteen and thirty-six until 1966, when it was estimated at fifty-two. It was listed as eighty-one in 1974, when Cleo's last postmaster, Mrs. Josie Baylor Bishop, retired, and the post office was closed. The tourist trade had begun to decline earlier, when U.S. Highway 83 between Menard and Junction bypassed Cleo to the east. The community had a population reported as eighty-one in the mid-1980s. It was recorded as three in 1990 and again in 2000. Source: Handbook of Texas Online.