Ann Arbor is a college town and the county seat of Washtenaw County, Michigan, United States.[7] The 2020 census recorded its population to be 123,851, making it the fifth-most populous city in Michigan.[8] It is the principal city of the Ann Arbor metropolitan area, which encompasses all of Washtenaw County and had 372,258 residents in 2020. Ann Arbor is also included in the Detroit-Warren-Ann Arbor combined statistical area and the Great Lakes megalopolis. Ann Arbor was founded in 1824 by John Allen and Elisha Rumsey.[9][10] It was named after the wives of the village's founders, both named Ann, and the stands of bur oak trees they found at the site of the town.[11] The University of Michigan was established in Ann Arbor in 1837,[12] and the city's population grew at a rapid rate in the early to mid-20th century.[13]