Sussex County is the northernmost county in the State of New Jersey. Its county seat is Newton. It is part of the New York City Metropolitan Area. As of the 2010 United States Census, the county had 149,265 residents, an increase of 5,099 (3.5%) from the 144,166 persons enumerated in the 2000 Census, making it the 17th-most populous county among the state's 21 counties. As of 2010 The Bureau of Economic Analysis ranked the county as having the 131st-highest per capita income ($49,207) of all 3,113 counties in the United States (and the ninth-highest in New Jersey).
Because of its topography, Sussex County has remained relatively rural and forested area. The county is part of the Skylands Region—a term promoted by the New Jersey Commerce, Economic Growth, & Tourism Commission to encourage tourism. In the western half of the county, several state and federal parks have kept the large tracts of land undeveloped and in their natural state. The eastern half of the county has had more suburban development because of its proximity to more populated areas and commercial development zones.
Most of Sussex County's economy was based on agriculture (chiefly dairy farming) and the mining industry. With the decline of these industries in the 1960s, Sussex County was transformed into a bedroom community that absorbed population shifts from New Jersey's urban areas. Recent studies estimate that 60% of Sussex County residents work outside of the county—many seeking or maintaining employment in New York City or New Jersey's more suburban and urban areas.