Newark is a transportation Mecca and is very easy to get into and out of.
By train
Newark Penn Station not to be confused with New York Penn Station is located just a few blocks from the heart of downtown Newark. It's a beautiful old McKim Mead & White building and worth visiting just on its own. It is served by Amtrak (http://www.amtrak.com) and New Jersey Transit's Northeast Corridor, North Jersey Coast Line, and Raritan Valley Line, (http://www.njtransit.com), with easy connections to New York, Philadelphia, Trenton, and points south and west. A PATH (http://www.panynj.com/path) train the Red Line connects Penn Station with Jersey City and the World Trade Center in NYC. Connections to other PATH lines can be made to Hoboken and 33rd St. in Manhattan. The Newark City Light Rail runs two lines in Newark, both terminating at Penn Station. The Newark City Subway Line formerly called the #7 City Subway and shown on maps as the blue line has service to Branch Brook Park and Grove Street, Bloomfield, NJ. The Newark Light Rail Line the orange line on maps operates between Penn Station and Broad Street Station. New Jersey Transit's Montclair-Boonton line, Morristown line and Gladstone Branch serve Broad St. station.
When taking the New Jersey train, realize that New York and Newark both have "Penn Stations". It is sometimes easy to mistake the conductor saying "New York" for "Newark" and vice versa, so be aware so you don't accidentally get off at the wrong station.
By car
Route 21 McCarter Hwy runs North-South along the railroad tracks a few blocks east of downtown. I-78 skirts the south edge of town and I-280 cuts across the north. Route 1/9 comes across the Pulaski Skyway from Jersey City and Manhattan via the Holland Tunnel. Take the Raymond Blvd. exit and drive along the Passaic River into downtown.