Best SEO and internet marketing services in Delaware County NY. Delaware County zip codes - 12406, 12421, 12438, 12459, 12474, 13731, 13739, 13740, 13751, 13752, 13753, 13755, 13756, 13757, 13774, 13775, 13782, 13783, 13786, 13788, 13804, 13806, 13839, 13842, 13846, 13847, 13856, 13860 Delaware County is a county in the U.S. state of New York. It is located on the south of the state. The county was founded in 1797. Delhi is the county’s seat. It was named so, because of the Delaware River which flows through the county. And the river was named after Thomas West (3rd Baron De La Warr, governor of Virginia in 1609). More than 47,000 people live there, according to the census in 2010. The county has the area of 1,467 square miles, where 1,442 square miles is land and the rest (25 square miles) is water. Delaware County is the fifth largest county in New York. Part of Catskill Mountains is situated in the county. The highest point is 3,520 foot (1,073 m) top of the Bearpen Mountain. The lowest point is along the Delaware River. The soil is very fertile there. The Delaware and Susquehanna rivers are the largest and boats are flowing on them. The famous State University of New York at Delhi is situated there in the county. People of such nationalities live there: White and Black African Americans, Native Americans, Pacific Islanders, Spaniards, Englishmen, and Germans. The majority of people speak English as their native and first language, but some speak Spanish and some German as well.