South Brunswick Township was incorporated by an act of the New Jersey Legislature on February 21, 1798. In the 18th and 19th centuries, the community was primarily agricultural. The Straight Turnpike, now U.S. Route 1, was constructed in 1804. The township got its name from New Brunswick, which in turn was named after the city of Braunschweig (called "Brunswick" in the Low German language), in state of Lower Saxony, in Germany. Braunschweig was an influential and powerful city in the Hanseatic League, later in the Holy Roman Empire, and was an administrative seat for the Duchy (and later Principality) of Hanover. Shortly after the first settlement of New Brunswick in colonial New Jersey, George, Duke of Brunswick-Lüneburg, and Elector of Hanover, of the House of Hanover (also known as the "House of Brunswick"), became King George I of Great Britain (1660–1727). Alternatively, the city derived its name from King George II of Great Britain, the Duke of Brunswick-Lüneburg.