Anna is a city in the U.S. state of Texas. Located in Collin County, its population was 16,896 at the 2020 U.S. census. Following the Ameri…Anna is a city in the U.S. state of Texas. Located in Collin County, its population was 16,896 at the 2020 U.S. census. Following the American Civil War, the Houston and Texas Central Railway resumed laying track north from Corsicana and passed through the area in 1872. By the time Anna was platted in 1883, it had a population of 20, two stores, a steam gristmill, and a Baptist church. A post office also opened in that year. In 1885, the railroad built a depot.