Alto is a town in Cherokee County, Texas, United States. The population was 1,225 at the 2010 census.
Alto is the closest municipality to the Caddo Mounds State Historic Site, an archaeological site dating back to 800 CE, featuring a prehistoric village and ceremonial center.
An early settler in the region was Martin Lacy, who built Lacy's Fort just to the west to the current site of Alto in around 1838. In 1838 and 1839, during the campaign to suppress the Córdova Rebellion, the fort served as an operations and supply base for the Third Militia brigade commanded by Maj. Gen. Thomas J. Rusk.
The town of Alto was laid out in 1849 and named for the Spanish word meaning "high," on account of the site's elevation on a drainage divide between the Neches and Angelina Rivers.
Alto is located at 31°39′0″N 95°4′26″W (31.650131, -95.073810).
According to the United States Census Bureau, the town has a total area of 1.7 square miles (4.4 km2), all land. Alto had a prisoner of war camp during World War II, which served the Cherokee County area.
As of the census of 2000, there were 1,190 people, 452 households, and 282 families residing in the town. The population density was 707.1 people per square mile (273.5/km2).