On March 6, 1840, the State of Ohio authorized the creation of Ottawa County. Residents took the Indian word for "trader" as the county's name. Ottawa County was originally part of territory set aside for Ohio's Indian people by the Treaty of Greenville. During the War of 1812, the Battle of Lake Erie occurred off the coastline of Ottawa County. The county's Johnson's Island served as a prisoner of war camp during the American Civil War.
Ottawa County is located in the northwestern portion of Ohio. The county seat is Port Clinton. It is the county's largest population center, with 6,391 residents in 2000. The county experienced a 2.4 percent increase in population between 1990 and 2000. This raised the number of residents to 40,985 people. Many of these new residents had left nearby Toledo. An average of 161 people lives in each of Ottawa County's 255 square miles. The county's average income was 27,370 dollars per person in 1999, with almost seven percent of the population living in poverty.
Ottawa County is primarily rural, with urban areas comprising five percent of the county's land area. Most residents find employment in retail businesses, with manufacturing establishments and service industries coming in second and third respectively. The county is a major tourist destination. Middle Bass Island and other various resorts along Lake Erie attract thousands of visitors each year. The oldest lighthouse in Ohio, Marblehead Lighthouse is located in the county as well. A large number of people visit the county to take part in boating, fishing, and other recreational activities along or on Lake Erie.
Ottawa County is the home of Camp Perry, the Ohio National Guard's primary training base.
Most voters in Ottawa County claim to be independents, yet in recent years, they have supported by slim margins Republican Party candidates at the national level.