Springfield Township is a township in Union County, in the U.S. state of New Jersey. The township is located on a ridge in northern-central New Jersey, within the Raritan Valley and Rahway Valley regions in the New York metropolitan area. As of the 2020 United States census, the township's population was 17,178, the highest recorded at any decennial census, an increase of 1,361 (+8.6%) from the 2010 census count of 15,817, which in turn reflected an increase of 1,388 (+9.6%) from the 14,429 counted in the 2000 census.

Berkeley Heights is a township in Union County, in the U.S. state of New Jersey. Located on a ridge in northern-central New Jersey, Berkeley Heights is a commuter town of New York City in the New York metropolitan area, nestled within the Raritan Valley region and also bordering both Morris and Somerset counties in the Passaic Valley region. As of the 2020 United States census, the township's population was 13,285, an increase of 102 (+0.8%) from the 2010 census count of 13,183, which in turn reflected a decline of 224 (−1.7%) from the 13,407 counted in the 2000 census.