Cisco is a city in Eastland County, Texas, United States. The population was 3,883 at the 2020 census, and 3,899 at the time of the 2010 cen…Cisco is a city in Eastland County, Texas, United States. The population was 3,883 at the 2020 census, and 3,899 at the time of the 2010 census. Cisco, at the intersection of U.S. Highway 183 and Interstate 20 in northwestern Eastland County, traces its history back to 1878 or 1879, when Rev. C. G. Stevens arrived in the area, established a post office and a church, and called the frontier settlement "Red Gap". About six families were already living nearby, and W. T. Caldwell was running a store a half mile to the west. In 1881, the Houston and Texas Central Railway crossed the Texas and Pacific, which had come through the year before, at a point near Red Gap, and the settlement's inhabitants moved their town to the crossing. The date the rails crossed, May 17, 1881, is considered by some to be Cisco's "birthday." Three years later, the town was officially recognized and a new post office granted; the town's name was changed to "Cisco" for John J. Cisco, a New York financier largely responsible for the building of the Houston and Texas Central.