The map above shows County Highways where Mercer County has jurisdiction. All other roads are under the ownership of their respective municipality, NJDOT, or NJTA.

Mercer County is located at a critical crossroads of commerce, education, healthcare and culture. Located in central New Jersey, roughly equidistant between New York City and Philadelphia, the County is within one of the most densely developed regions in the nation, with approximately 10% of the US population living within 75 miles. Nearly all north-south surface traffic on the eastern seaboard passes through Mercer County.  Major facilities include the New Jersey Turnpike, Interstates I-95 and I-295, US Route 1, the Northeast Corridor commuter rail line (three rail operators serve Trenton Station), two freight rail lines (CSX and Conrail), inter-regional oil and natural gas pipelines, and a bulk freight seaport, as well as the Trenton-Mercer Airport, the third busiest commercial air terminal in New Jersey.  In addition, state highways (especially US 206 and NJ 31) provide arterial connectors between I-95 in Mercer County and US 202/I-287 in Hunterdon and Middlesex Counties. County highways provide connections from State and Federal roadways to our towns and adjacent Counties.

Far more than just laying pathways to get from one place to another, transportation infrastructure has played a fundamental role in shaping the physical, social, environmental and economic landscape in cities and regions all around the nation. This transportation infrastructure is the skeleton on which all land development in Mercer County depends. Land development concurrently is key to both economic and environmental sustainability.

With nearly 400,000 residents and thousands of local businesses located within 226 square miles of the County, it is crucial to work together to promote a more economically viable, environmentally sustainable and livable area. Transportation planning at the regional scale is critical to our economic vitality, environmental health and community cohesion. To meaningfully influence economic and environmental impacts associated with development, land use and transportation officials must act at a level where central cities and suburbs are considered together.

The Mercer County Department of Planning works with the Division of Engineering to plan for the physical development of our territory, as enabled by New Jersey's County Planning Act.  Under that statute (NJSA 40:27-1 et seq.), the County is responsible for approximately 180 miles of County Highway and almost 900 drainage structures. Beyond system preservation and enhancement, the County is responsible to review land development applications to address a variety of impacts on the highway and stormwater networks, ranging from capacity, safety, air and water quality, and travel mode choice.

Though some new highways connections are necessary, most of the County planning function is reserved to road preservation rather than new lane miles. The projects listed on this page are larger scale transportation projects that may be of interest to our residents.