The Ohio Company of Associates, also known as the Ohio Company, was a land company whose members are today credited with becoming the first non-Native American group to permanently settle west of the Allegheny mountains. In 1788 they established Marietta, Ohio, as the first permanent settlement of the new United States in the newly organized Northwest Territory.

Marietta is a city in, and the county seat of, Washington County, Ohio, United States. It is located in southeastern Ohio at the confluence of the Muskingum and Ohio Rivers, 11 miles (18 km) northeast of Parkersburg, West Virginia. As of the 2020 census, Marietta has a population of 13,385 people. It is the principal city of the Marietta micropolitan area, which includes all of Washington County, and is the second-largest city in the Parkersburg–Marietta–Vienna combined statistical area.