Killeen is a city in Bell County, Texas, The United States. The population was 86,911 at the 2000 census. As of 2009, Killeen had 119,510 people. In 2010 Killeen's population shot to 127,921. Then in 2011 the population shot up to 140,021. It is a "principal city" of the Killeen–Temple–Fort Hood Metropolitan Statistical Area.
Killeen is directly adjacent to the main cantonment of Fort Hood, and as such its economy heavily depends on the post and the soldiers (and their families) stationed there.
In 1881, the Gulf, Colorado and Santa Fe Railway extended its tracks through central Texas, buying 360 acres (1.5 km2) a few miles southwest of a small farming community known as Palo Alto, which had existed since about 1872. The railroad platted a 70-block town on its land and named it after Frank P. Killeen, the assistant general manager of the railroad. By the next year the town included a railroad depot, a saloon, several stores, and a school. Many of the residents of the surrounding smaller communities in the area moved to Killeen and by 1884 the town had grown to include about 350 people, served by five general stores, two gristmills, two cotton gins, two saloons, a lumberyard, a blacksmith shop, and a hotel. Killeen expanded as it became an important shipping point for cotton, wool, and grain in western Bell and eastern Coryell counties. About 780 people lived in Killeen by 1900. Around 1905, local politicians and businessmen convinced the Texas legislature to build bridges over Cowhouse Creek and other streams, doubling Killeen's trade area. A public water system began operation in 1914 and its population had increased to circa 1,300 residents.