 It also serves as the main north–south highway through the central part of Newark, connecting attractions in Downtown Newark with Newark Airport.The portion of Route 21 through Newark is a surface arterial that runs alongside the elevated Northeast Corridor rail line through the southern part of the city and continues north through Downtown Newark while the portion north of Downtown Newark is a freeway.Route 21 intersects many major roads including Interstate 78, Route 27, and Interstate 280 in Newark, Route 7 in Belleville, and Route 3 in Clifton.