Although Mt. Lebanon did not become a town until 1912, the name Mt. Lebanon had been in use for more than a half-century before. Sometime in the 1850s, the Rev. Joseph Clokey, pastor of St. Clair Church (now the site of Mt. Lebanon Evangelical Presbyterian Church on Washington Road), made a pilgrimage to the “Holy Land,” and brought back two Cedar of Lebanon trees from the Taurus Mountains in what was then Turkey, which he planted on his property.

At the time, Mt. Lebanon was part of Upper St. Clair. A few years later, the area was designated part of Scott Township, but the name remained. By 1883, a postal station in a general store at the corner of Washington and Bower Hill roads was referred to as the Mt. Lebanon Post Office.

The first trolleys from Pittsburgh came to Mt. Lebanon in 1901, quickly followed by the Mt. Lebanon Plan of Homes, in the center of town, including Shady Drive East and West. The next year, the Clearview Plan of Homes was plotted out by the Mt. Lebanon Land & Trust Company.

The rapid development spurred a desire for independent government, and residents petitioned the court to split off from Scott. The proposal was put up to a referendum, which failed to pass the first two times on the ballot. The motion carried on the third try, and on February 6, 1912, the Allegheny County Court of Quarter Sessions declared Mt. Lebanon a township.