The Somerset / Hunterdon / Mercer Counties, NJ atlas shows U.S., State and Interstate Highways. This atlas is fully street-indexed, and contains a Government Guide, ZIP codes, wildlife management areas, schools, parks, airports, golf courses, railroad routes and other points of interest. Every day, government transportation officials, road construction crews and local developers are working to make your atlases out of date. That's why you need Hagstrom. Our skilled researchers and cartographers are constantly alert for changes that could affect your travel plans.