The Monongahela River (// mə-NONG-gə-HEE-lə, /--/ -HAY-) — often referred to locally as the Mon (//) — is a 130-mile-long (210 km) river on the Allegheny Plateau in north-central West Virginia and southwestern Pennsylvania, which flows from south to north. The Monongahela joins the Allegheny River to form the Ohio River at Pittsburgh.
- There are several ways to pronounce this word that are acceptable. From "Geographical Names" of Merriam-Webster's Collegiate Dictionary, Eleventh Edition (2009): //, // or //.
- U.S. Geological Survey. National Hydrography Dataset high-resolution flowline data. The National Map, accessed August 15, 2011