Settled in 1805, Jefferson County grew around the city of Watertown, the county seat. Established on the banks of the Black River as the first industrial town in this rugged upstate wilderness, Watertown became a major trade center and manufacturing base. Early residents built a reputation for quality products and Yankee ingenuity. The Woolworth's Five and Dime stores began here, as well as Philadelphia Cream Cheese and Thousand Island Dressing.

Jefferson County's modern-day economy is greatly diversified. Making fine use of their abundant natural resources, dairy farming, papermaking and food processing remain prominent industries. Manufacturing of railroad and industrial machinery and medical equipment are also key industries. The activation in the 1980's of the military base Fort Drum brought an upsurge in trade and construction.

Magnificent Lake Ontario greatly influences the climate in Jefferson County, NY. This massive Great Lake remains relatively warm through the winter, and lends moisture to the air masses moving across it from the west. "Lake effect" snowfalls occur predominantly in the southern portion of the county. Watertown is fondly known as "Snowtown, USA", with an average of 101 inches of snow annually, though up to 200 inches may occur. Lake Ontario tends to moderate extreme temperatures, keeping Jefferson County a cool 68 degrees in the summer, and in the winter months, an average of 21 degrees.

Sports enthusiasts enjoy every season here. World-class fishing and boating opportunities abound. Diving and exploring the many shipwrecks scattered along the shoreline of the lake has become very popular. Kayaking among the islands and white-water rafting along the Black River attracts many boaters. Two of Jefferson County's islands rank as some of the largest of the 1000 islands. Wellesly Island contains the major selection of campsites in the region, from secluded forest sites to shorefront. Three state parks are found here, Dewolf Point, Mary Island, accessible only by boat, and the largest, Wellesly Island State Park. Grindstone Island holds one of the finest fishing spots, the Canoe-Picnic Point State Park, also accessible only by boat.

The main population in Jefferson County is found in Watertown and Fort Drum. Other major towns and villages include Carthage, Chaumont, Sackets Harbor, Cape Vincent and lovely Alexandria Bay, known as the heart of the Thousand Islands. Fifty-nine communities make up the region. The Census 2000 population was 111,738.

Jefferson County, New York, surrounded by the finest in scenic natural splendor, is a premier location to live and work.