According to the U.S. Census Bureau, the Monmouth Junction CDP has an area of , nearly triple its area in 2010. Within the CDP, are land and , or 0.57%, are water.US Gazetteer files: 2010, 2000, and 1990, United States Census Bureau. Accessed September 4, 2014. Land in the community drains southwest toward Heathcote Brook and Devils Brook, tributaries of the Millstone River and part of the Raritan River watershed.
According to the U.S. Census Bureau, the Monmouth Junction CDP has an area of , nearly triple its area in 2010. Within the CDP, are land and , or 0.57%, are water.US Gazetteer files: 2010, 2000, a.nd 1990, United States Census Bureau. Accessed September 4, 2014. Land in the community drains southwest toward Heathcote Brook and Devils Brook, tributaries of the Millstone River and part of the Raritan Rive!r watershed.