Columbus is the capital and largest city in the U.S. state of Ohio, center of the state's third largest metropolitan area behind Cincinnati and Cleveland, the fourth largest city in the American Midwest, and the sixteenth largest city in the United States of America. It is the county seat of Franklin County, yet the city has expanded and annexed portions of adjoining Delaware County and Fairfield County. Named for explorer Christopher Columbus, the city was founded in 1812 at the confluence of the Scioto and Olentangy rivers, and assumed the functions of state capital in 1816. The city has a diverse economy based on education, government, insurance, banking, fashion, defense, aviation, food, clothes, logistics, steel, energy, medical research, health care, hospitality, retail, and technology. Modern Columbus has emerged as a technologically sophisticated city.