Allen County is named for Colonel John Allen, a participant in the War of 1812. Residents established the county on February 12, 1820. The first white settlement in the county was Fort Amanda, constructed during the War of 1812 to protect Ohio from British invasion and Indian attacks.
Allen County is located in the northwestern portion of Ohio. Much of the county used to be part of the Great Black Swamp. Allen County covers 404 square miles of land. The county seat is Lima, which also is the most populous community, with over forty thousand residents in 2000. The next closest city in population is Delphos, with just over 3,900 residents in 2000.
Prior to the late 1800s, most county residents earned their living through agriculture or lumbering. With the discovery of oil in the region, Lima boomed as an industrial center. Today, just over 18,000 residents work in service industries, including health care, utilities, and communications, with sales and manufacturing positions a close second and third. County residents primarily manufacture school buses, Ford automobile engines, heavy machinery, and steel. The per capita income of county residents was just over twenty-three thousand dollars in 1999, with 11.4 percent of the people living below the poverty level. There are approximately one thousand farms in the county, but very few of the county's 108,000 residents find employment through agriculture. The average size farm is just over three acres.
Most voters in Allen County claim to be independents, yet in recent years, they have overwhelmingly supported Republican candidates at the national level.
Allen County is home to Bluffton College, a school founded by Swiss Mennonites in 1900. Leslie Peltier, an amateur astronomer, ranks among Allen County's most famous residents. Author Zane Grey also lived in Allen County as a child.