Alliance is a city in the U.S. state of Ohio. Most of the city is located in northeast Stark County while a small portion is in adjacent Mahoning County. The population was 22,322 as of the 2010 census. Alliance was established in 1854 by combining three smaller communities. The city was a manufacturing and railroad hub for much of the 20th century and is also associated with the state flower of Ohio, the scarlet carnation, and is known as "The Carnation City". The University of Mount Union, a private liberal arts college established in 1846, is located in Alliance.Most of the city is part of the Canton–Massillon, OH Metropolitan Statistical Area, while the small portion of the city in Mahoning County is within the Youngstown–Warren–Boardman, OH-PA Metropolitan Statistical Area.