[3] Major General Edward Braddock's Expedition of 1755 passed through the southwestern portion of the area that became Addison Township.

[3] Somerfield was laid out on the western edge of the township about 1816 by Philip D. Smyth,[3] but the town was abandoned and covered over by the Youghiogheny River Lake in the 1940s.

U.S. Route 40 passes through the southwestern corner of Addison Township, crossing over the Youghiogheny River Lake from Fayette County in the west, passing through the borough of Addison, and continuing south into Maryland.

The racial makeup of the township was 99.71% White, 0.10% Native American, 0.10% Asian, 0.10% from other races.

Media related to Addison Township, Somerset County, Pennsylvania at Wikimedia Commons