It is entirely possible that the very end of Long Hill Road is supposed to be part of CR 620, as Clove Road in Little Falls is CR 620 and so the two similarly numbered roads would connect. However, I have represented the roads based on the NJDOT straight-line diagrams.
| Mile | Street Name | Feature (West to East) |
| 0.00 | CR 631 BEGINS, Little Falls Twp | |
| 0.09 | Main St | [Lindsley Rd, CR 604] |
| 0.47 | Main St | Fire station {flashing signal} |
| 0.51 | Main St | Newark-Pompton Tpk, NJ 23 {signal} |
| 0.61 | Main St | Unnamed stream {culvert} |
| 0.64 | Main St | Erie Railroad {at-grade crossing} |
| 1.00 | Main St | Unnamed river {bridge} |
| 1.14 | Main St | [Montclair Ave, CR 645] |
| 1.20 | Main St | Union Ave, CR 646 {signal} |
| 1.43 | Main St | [Center Ave, CR 643] |
| 1.50 | Main St | [Stevens Ave, CR 616] {signal} |
| 1.54 | Main St | (Paterson Ave, CR 639) |
| 1.71 | Main St | [1 Ave, CR 637] |
| 2.01 | Main St | Peckman River {bridge} |
| 2.25 | Main St | (Browertown Rd, CR 635) |
| 2.25 | Main St becomes Long Hill Rd | |
| 2.75 | Long Hill Rd | (Notch Rd, CR 633) {signal} |
| 2.77 | Long Hill Rd | Erie Railroad {overpass} |
| 2.95 | Long Hill Rd | [Ridge Rd, CR 641] |
| 3.00 | Long Hill Rd | Unnamed stream {culvert} |
| 3.23 | Long Hill Rd | [Francisco Ave, CR 612] |
| 3.67 | Long Hill Rd | (Clove Rd, CR 620) |
| 3.83 | CR 631 ENDS, Little Falls Twp | |