Willoughby is a city in Lake County, Ohio, United States and is a suburb of Cleveland. The population was 22,268 at the 2010 census.
Willoughby's first permanent settler was David Abbott in 1798, who operated a gristmill. Abbott and his family were said to have had close relations with a band of Indians along the banks of the local river, which the Indians called the "Sha-ga-rin" meaning "Clear Water." This river was later called the Chagrin River, though the origin of the name remains in dispute.
In 1835, the village was permanently named "Willoughby" in honor of Dr. Westel Willoughby, Jr., a public health official that the founders of a short-lived Medical College, which was based in the city, hoped to attract to the area. Many historical buildings from this period survive to this date, affording the downtown Willoughby area some outstanding specimens of 19th century architecture.
In World War I, the U.S. Army chose Willoughby as the site for a chemical weapons plant producing lewisite.
Over time, Willoughby sent citizens into every major U.S. military conflict. Several memorials and historical relics are displayed in Wes Point Park, the center of downtown Willoughby, to honor those that have served.
Willoughby is the only town in America that has belonged, at one time or other, to six counties (Washington, Jefferson, Trumbull, Geauga, Cuyahoga, and Lake).
Willoughby is located at 41°38′45″N 81°24′35″W (41.645915, -81.408515).
According to the United States Census Bureau, the city has a total area of 10.34 square miles (26.78 km2), of which 10.25 square miles (26.55 km2) is land and 0.09 square miles (0.23 km2) is water.
At the 2010 census there were 22,268 people in 10,413 households, including 5,716 families, in the city. The population density was 2,172.5 inhabitants per square mile (838.8/km2).