- Southern Terminus:
- Hope-Bridgeville Road (CR 519) in Hope
- Northern Terminus:
- Maple Avenue (Orange CR 16) at the New York-New Jersey state line
- 43.71 miles
- Warren, Sussex
CR 521 is a north/south route running through the northwest corner of New Jersey. It begins at CR 519 in Hope, just south of I-80, and runs north to Blairstown, where it is multiplexed with NJ 94 for a few blocks. It then splits off and runs northeast to Newton. From there, it follows a semicircular route around the Bear Swamp Wildlife Management Area, turning northwest onto Kemah Mecca Lake Road and then northeast onto West Owassa Turnpike, which ends at US 206. CR 521 is multiplexed with US 206 until just before it crosses the Delaware River to Pennsylvania and then splits off onto River Road, which runs northeast to the New York-New Jersey state line. It turns into Maple Avenue (Orange CR 16) at the state line. The entire length of CR 521 is a two-lane undivided road.