Belpre is a city in Washington County, Ohio, United States, along the Ohio River. It is part of the Parkersburg-Marietta-Vienna, WV-OH Metropolitan Statistical Area. The population was 6,660 at the 2000 census. The city was also the second settlement in the Northwest Territory after Marietta, located just upriver and today the county seat of Washington County. The town was originally named Belle Prairie or "Beautiful Prairie. " The Steven Soderbergh film Bubble, released in 2006, was filmed in Belpre and Parkersburg using an all-local cast. total area of 3.5 square miles (9.1 km), of which, 3.5 square miles (9.1 km) of it is land and 0.04 square miles (0.10 km) of it (0.85%) is water.