Is the Hudson River in New Jersey? No, It's a New York River

The Hudson River flows entirely within New York State. It runs over 300 miles from Lake Tear of the Clouds in the Adirondack Mountains south to New York Harbor in Manhattan.

While the river forms part of the border between New York and New Jersey near its mouth, the watercourse itself is in New York. The New Jersey side includes the Hudson Palisades and waterfront cities like Jersey City and Hoboken, but the river belongs to New York.