South Euclid is a city in Cuyahoga County, Ohio, United States. It is an inner-ring suburb of Cleveland located on the city's east side. As of th…South Euclid is a city in Cuyahoga County, Ohio, United States. It is an inner-ring suburb of Cleveland located on the city's east side. As of the 2020 census, the population was 21,883. The land currently comprising South Euclid was part of the Western Reserve, obtained via treaty with the Iroquois confederation in 1796 by the Connecticut Land Company. In 1797, Moses Cleaveland named the area east of the Cuyahoga River Euclid, after the Greek mathematician and "patron saint" of surveyors. Euclid Township was officially formed in 1809. In 1828, Euclid Township was divided into nine districts, with South Euclid becoming district two.