Lake County, Ohio

Lake County is a county in the U.S. state of Ohio. As of the 2020 census, the population was 232,603. Its county seat is Painesville, and its largest city is Mentor.

The county was established on March 6, 1840, from land given by Cuyahoga and Geauga counties. Its name is derived from its location on the southern shore of Lake Erie and the fact that the majority of the county’s land lies beneath Lake Erie. Lake County is part of the Cleveland, OH Metropolitan Statistical Area.

The land that became Lake County was home to the indigenous Erie people prior to the arrival of the French in the region during the early 1600s and was considered by the French to be part of their Colony of New France. After France's defeat in the Seven Years' War in 1763, France ceded the area to Great Britain, and the area became part of the Province of Quebec through the Quebec Act of 1774. Following the American Revolutionary War, it became part of the Connecticut Western Reserve in the Northwest Territory, then was purchased by the Connecticut Land Company in 1795. It was separated out of Geauga County in March 1840.

Although today the county is mostly suburban, Lake County was once known as a rural country retreat for wealthy Cleveland residents. During the early 1900s, many wealthy families in Cleveland maintained large estates in the county for use as their summer homes.

According to the United States Census Bureau, the county has an area of 979 square miles (2,540 km²), of which 227 square miles (590 km²) is land and 752 square miles (1,950 km²) (77%) is water. It is Ohio's smallest county by land area but the third-largest by total area, with said area owing to land beneath the lake (which is owned by the county).

The county’s coast line along Lake Erie spans 31 miles. Additionally, Lake County has an international border with Ontario (across Lake Erie).

Ridges on the Lake Plain physiographic region, and on which some roads are laid, are beaches formed by the various glacial lakes which occurred as the glaciers receded. Lake Maumee was the highest glacial lake at about 760 feet, and left Maumee II beach. Whittlesey beach, formed by Lake Whittlesey at 740 feet, is known as South Ridge. Arkona beach (Lake Arkona) is Middle Ridge, and occurs at about 690 feet. North Ridge is the remnant of Warren beach (Lake Warren), at an elevation of 685 feet. Elkton beach is the northernmost ridge, at 625 feet, an occurred at the time of Lake Elkton. Lake Shore Boulevard follows Elkton beach in Mentor Township.

Mentor Marsh, an abandoned channel of the Grand River, is an Ohio State Nature Preserve.