county, north-central New York state, U.S., bordered by Lake Ontario to the northwest and the Oswego and Oneida rivers and Oneida Lake to the south. Other waterways include the Salmon and Little Salmon rivers and the New York State Canal System and its constituent Erie and Oswego canals. Most of the county consists of lowlands, except for the northeastern corner, which rises into a plateau region. The county is dotted with swamps and stands of oak and hickory trees. State parks are Selkirk Shores and Battle Island.
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