Upper Merion Township is a township in Montgomery County, Pennsylvania, United States. The population was 28,395 at the 2010 U.S. Census. Located from Philadelphia, it consists of the villages of King of Prussia, Swedeland, Swedesburg, Gulph Mills, and Wayne.
The westernmost part of the township is the site of Valley Forge, as well as comprising the largest part of the Valley Forge National Historical Park. The township is the home of the King of Prussia Mall. King of Prussia is also a major office park hosting firms such as Lockheed Martin and GlaxoSmithKline.
The name Merion originates with the county of Merioneth in north Wales. Merioneth is an English-language translation of the Welsh Meirionnydd.