Gilbertsville is a census-designated place (CDP) in northwest Montgomery County, Pennsylvania, United States. It is located in Douglass Township at the junction of Routes 73 and 100. The population was 4,832 at the 2010 census, and the ZIP code is 19525. The name is also applied to an indeterminate adjacent section of New Hanover Township served by the Gilbertsville Post Office, and in fact the New Hanover Township offices are located in an area considered to be part of Gilbertsville. Boyertown School District covers the town of Gilbertsville. Gilbertsville began when the descendants of William Gilbert, an English astronomer, physician, and physicist, decided to permanently move to America. Although many of the Gilberts fought for America in the Revolutionary War, Abijah Gilbert did not relocate his family until 1790. In the fall of 1789, 1,000 acres (4.0km2) of land were purchased for the modern-day price of $2000. It was the first land purchased from the Morris Trust in Montgomery County, Pennsylvania. The Gilberts purchased more land in later years. A Gilbert Family letter recalls that as Abijah Gilbert's son, Joseph Thomas Gilbert, was disembarking in Philadelphia, George Washington patted him on the head and said, "A fine, rosy-cheeked English boy, who will make a good American Citizen."