Niles is a city in Trumbull County, Ohio, United States. The city's population was 20,932 at the 2000 census. It is part of the Youngstown-Warren-Boardman, OH-PA Metropolitan Statistical Area.
Located in the nation's former industrial belt, the city's economy focused initially on iron manufacturing but later diversified to include steel and glass production. Niles was adversely affected by the decline of the manufacturing sector throughout the northern United States in the 1970s.
Niles was founded in 1806 by James Heaton, who owned one of the first iron-ore processing plants in Ohio. The town originally went by the name of Heaton's Furnace but was later renamed Nilestown, after Hezekiah Niles (editor of the Niles Register, a Baltimore newspaper). In 1843, the name was shortened to Niles. In the early 19th century, Heaton built a forge and, later, a charcoal blast furnace in the area just east of what is now the city's central park, on the west side of Mosquito Creek. Heaton is credited with producing the first bar iron in Ohio.