Warren is a city in and the county seat of Trumbull County, Ohio, United States. The municipality is located in northeastern Ohio, approximately 14 miles (23 km) northwest of Youngstown and 56 miles (90 km) southeast of Cleveland.
The population was 41,558 at the 2010 census. Warren is the second largest city in the Youngstown-Warren-Boardman, OH-PA Metropolitan Statistical Area, and anchors the northern part of that area.
Ephraim Quinby founded Warren in 1798, on 441 acres (1.78 km2) of land that he purchased from the Connecticut Land Company, as part of the Connecticut Western Reserve. Quinby named the town for the town's surveyor, Moses Warren. The town was the county seat of the Western Reserve, then became the Trumbull County seat in 1801.
In 1833, Warren contained county buildings, two printing offices, a bank, five mercantile stores, and about 600 inhabitants.
Warren had a population of nearly 1,600 people in 1846. In that same year the town had five churches, twenty stores, three newspaper offices, one bank, one woolen factory and two flourmills. In June 1846, a fire destroyed several buildings on one side of the town square, but residents soon replaced them with new stores and other businesses. Warren became an important center of trade for farmers living in the surrounding countryside during this period.