Port Arthur is a city in Jefferson County within the Beaumont−Port Arthur Metropolitan Statistical Area of the U.S. state of Texas. A small portion extends into Orange County. It is 91 mi east of Houston. It is host to the largest oil refinery in the United States.The population of Port Arthur was 53,818 at the 2010 census. Early attempts at settlements in the area had all failed. However, in 1895, Arthur Stilwell founded Port Arthur, and the town quickly grew. Port Arthur was incorporated as a city in 1898 and soon developed into a seaport. It eventually became the center of a large oil refinery network. The Rainbow Bridge across the Neches River connects Port Arthur to Bridge City.