 northumberland is a borough in northumberland county, pennsylvania, united states. the population was 3,804 at the 2010 census. ==history== northumberland was founded in 1772.hirsch, 25; bell, 517-18. the land that became northumberland was purchased from the iroquois in the first treaty of fort stanwix in 1768, and the village was laid out in 1772. during the american revolution, northumberland was evacuated during the big runaway in 1778, and only finally resettled in 1784."national register of historic places registration: northumberland historic district". northumberland was the american home of eighteenth-century british theologian, dissenting clergyman, [[natu
Boroughs_in_Northumberland_County,_Pennsylvania Boroughs_in_Pennsylvania Populated_places_established_in_1772 Populated_places_on_the_Susquehanna_River