Erie (; EER-ee) is a city on the south shore of Lake Erie and the county seat of Erie County, Pennsylvania, United States. The city was named for the Native American Erie people who lived in the area until the mid-17th century. Erie is the fifth-largest city in Pennsylvania, and the largest city in Northwestern Pennsylvania, with a population of 94,831 at the 2020 census. The estimated population in 2021 had decreased to 93,928. The Erie metropolitan area, equivalent to all of Erie County, consists of 266,096 residents. The Erie-Meadville combined statistical area had a population of 369,331 at the 2010 census. Erie is halfway between the cities of Buffalo, New York, and Cleveland, Ohio, and due north of Pittsburgh, Pennsylvania. Erie's manufacturing sector remains prominent in the local economy, though healthcare, higher education, technology, service industries, and tourism are emerging as significant economic drivers. Over four million people visit Erie each summer for recreation at Presque Isle State Park and attractions such as Waldameer Park. Erie is known as the "Flagship City" because of its status as the home port of Oliver Hazard Perry's flagship Niagara. Erie won the All-America City Award in 1972. In 2012, Erie hosted the Perry 200, a commemoration celebrating 200 years of peace between Britain, America, and Canada following the War of 1812 and Battle of Lake Erie.

Warren County is a county located in the U.S. state of Pennsylvania. As of the 2010 census, the population was 41,815. Its county seat is Warren. The county was formed in 1800 from parts of Allegheny and Lycoming counties; attached to Crawford County until 1805 and then to Venango County until Warren was formally organized in 1819.Warren County makes up the Warren, PA Micropolitan Statistical Area.

Cattaraugus County is a county in western New York, with one side bordering Pennsylvania. As of the United States 2020 census, the population was 77,042. The county seat is Little Valley. The county was created in 1808 and later organized in 1817.Cattaraugus County comprises the Olean, NY Micropolitan Statistical Area, which is included in the Buffalo-Cheektowaga-Olean, NY Combined Statistical Area. Within its boundaries are the Allegany Indian Reservation of the Seneca Nation of New York, and the Allegany State Park. The Allegheny River runs through the county.

Bradford is a city in McKean County, Pennsylvania, United States, close to the border with New York State and approximately 78 miles (126 km) south of Buffalo, New York. Bradford is the principal city in the Bradford, PA Micropolitan Statistical Area. The population was 8,770 at the 2010 United States Census.