On March 12, 1783, the Commonwealth of Pennsylvania, through the Act of Assembly, appropriated a large tract of land that ran from the northwestern side of the Allegheny River all the way to the Ohio border. This land was then parceled into smaller lots ranging in size from 200 to 300 acres. The cluster of parcels between the Allegheny River and Buffalo Creek came to be known as Old Buffalo. Businessmen in the East and settlers moving west across the Allegheny Mountains could purchase parcels for silver or gold. Additionally, soldiers who fought for the newly formed United States during the American Revolution, 1777 to 1781, were issued certificates in lieu of payment. The certificates were "depreciated" in face value based on the soldier's time in service. As soldiers moved west in the country's expansion, they would use these certificates to purchase available land. Thus the lots came to be known as "depreciation lots". One of the most notable of these depreciation lot owners was Dr. Benjamin Franklin. On November 1, 1787, he purchased eleven of these lots while at the Merchants Coffee House in Philadelphia. He paid between one penny and two pence per acre.
Seventeen years later, on March 12, 1800, portions of Allegheny, Lycoming, and Westmoreland Counties were sectioned off and combined to form a new county - Armstrong County. In 1803, the county was further divided into six townships, Buffalo (Old Buffalo as it was called) was the fifth of these townships. Given the unwieldy size of "Old Buffalo", it was decided to divide it into four smaller townships. Of the resulting townships, the southern-most was named South Buffalo Township and was incorporated in 1847.
In the late Eighteenth and early Nineteenth Centuries, overland travel was extremely difficult with most "roads" able to accommodate only a single horse and rider. As a result, the Allegheny and Kiskiminetas Rivers provided the safest and most reliable travel routes. The early settlers in the Township chose to live near or along these access routes as well as the rivers' tributaries, including Buffalo Creek.
Located at the junction of the Allegheny River, Kiskiminetas River, and Buffalo Creek, Freeport became the hub of trade for all of the farmers and merchants in the area. Taking advantage of the "Free Port" to market their goods, this early river town gave rise to industries including gristmills and sawmills.
As the Township grew, many small towns formed at intersecting waterways and along overland trade routes. Towns and villages such as Boggsville, Clinton, McVille, and Slate Lick became integral to the region's growing economy. Jacob Brickner operated his mills in Boggsville, located at the confluence of Cornplanter Run and Buffalo Creek in 1800. John Harbison, one of the first settlers to the area, established a sawmill along Buffalo Creek in 1804. His wife, "Massey," was the heroine of an Indian raid and was known throughout the region for her valor. Nicholas Best operated a pottery near Slate Lick from 1843-1845. And, James Doughtery built the first local windmill in McVille. It was here that he made hatchets and nails for the local community. Also established in McVille was South Buffalo Township's first post office. On May 5, 1864, Robert McCaslin became the first postmaster for the Township.