Hadley is an unincorporated community in Mercer County, Pennsylvania, United States.

[1] The community is situated along Pennsylvania Route 358, 12.9 miles (20.8 km) north of Mercer.

As a result, when the Lake Shore Railroad was built across the township and a station erected on land he donated, the locality was named Hadley in honor of his contributions.

The Hadley post office was established in May 1868, with David Pattison as postmaster.

Hadley Presbyterian Church was organized in 1875; its building was dedicated the following year.