The first settlers were English Quakers, with German immigrants settling later and establishing it as an important agricultural community.

The Emig Mansion, Sinking Springs Farms, and Willis House are listed on the National Register of Historic Places.

At the 2000 census there were 12,700 people, 4,951 households, and 3,688 families living in the township.

There were 5,122 housing units at an average density of 322.5 per square mile (124.5/km2).

York Barbell, a reseller of barbells and other equipment for weight training and bodybuilding and the home of the USA Weightlifting Hall of Fame, is headquartered in Manchester Township.