Lebanon, formerly known as Steitztown, is a city in and the county seat of Lebanon County, Pennsylvania, United States. The population was 25,477 at the 2010 census, a 4.2% increase from the 2000 count of 24,461. Lebanon is located in the central part of the Lebanon Valley, 26 miles (42km) east of Harrisburg and 29 miles (47km) west of Reading. Native tribes in the area of what is now Lebanon included the Shawnee, Susquehannock, Gawanese, Lenape (or Delaware), and Nanticoke peoples. Lebanon was then settled in 1720 by European colonists, many with the family names of "Steitz" and "Light", along a creek that was then named "Steitz Creek". The Light patriarchs built a fort to protect against Indians and named it "Light's Fort" during this time. The town was laid out in 1753. The town was incorporated as a borough on February 20, 1821 and became a city on November 25, 1885. It adopted the commission form of government, consisting of four councilmen and a mayor. In 1900, 17,628 people lived in Lebanon; in 1910, 19,240 people lived there; in 1920, 24,643 people lived there; and in 1940, 27,206 people lived in Lebanon, Pennsylvania.