Houses on the northern side of Market Street (State Route 14) in Washingtonville, Ohio, United States. Picture is taken on the Columbiana County side of the street, while the houses are on the Mahoning County side. – Nyttend, Public domain – Wikimedia Commons Washingtonville is located in Ohio. About 712 people live here (as of 2020). Between 2010 and 2020, the population declined from 801 to 712. There are about 25 streets in Washingtonville. The region was founded in 1832. The postal codes are 44490. Washingtonville is human settlement in Ohio, United States of America.