Killeen is a city in Bell County, Texas, United States. According to the 2020 census, its population was 153,095, making it the 19th-most populous city in Texas and the largest of the three principal cities of Bell County. It is the principal city of the Killeen–Temple–Fort Hood Metropolitan Statistical Area. Killeen is 55 miles (89 km) north of Austin, 125 miles (201 km) southwest of Dallas, and 125 miles (201 km) northeast of San Antonio.

Killeen is directly neighboring the main cantonment of Fort Hood. Its economy depends upon the endeavors of the post, and the soldiers and their families stationed there. It is known as a military “boom town” because of its rushed growth and high influx of soldiers.

In 1881, the Gulf, Colorado and Santa Fe Railway outstretched its tracks through central Texas, buying 360 acres (1.5 km) a few miles southwest of a little farming community known as Palo Alto, which had existed previously about 1872. The railroad platted a 70-block town upon its home and named it after Frank P. Killeen, the partner general overseer of the railroad. By the neighboring 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. By 1884, the town had grown to attach 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. By 1900, its population was just about 780.