Milton is a borough in Northumberland County, Pennsylvania, United States, on the West Branch Susquehanna River, 50 miles (80 km) north of Harrisburg, located in Central Pennsylvania's Susquehanna River Valley. It is approximately 10 miles upriver from the mouth of the West Branch Susquehanna River and about 30 miles downriver of Williamsport.

Northumberland County is a county in the Commonwealth of Pennsylvania. As of the 2020 census, the population was 91,647. Its county seat is Sunbury. The county is part of the Central Pennsylvania region of the state.