At one time, the highway continued south, for another three miles, to a junction with SR 509 in Westfield. That highway is now shown on the NJDOT straight-line diagrams as SPUR 509, but Union County continues to sign it as SR 577.
SR 577 splits into two alignments in downtown Millburn, near the train station. (SR 527, which crosses the tracks there, does so as well.) The alignments are combined in this log.
The section of Prospect Avenue in West Orange between Mount Pleasant Avenue, NJ 10, and Northfield Avenue, SR 508, is still signed by Essex County as SPUR 577, but NJDOT carries it in its straight-line diagrams as CR 677.
| Mile | Street Name | Feature | ||
Road continues northward as  Pompton Ave |
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| 9.96 | Northern terminus of , Verona Twp, Essex Co |
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| 9.96 | Prospect Ave |  Bloomfield Ave |
Bloomfield Ave |
|
| 9.71 | Prospect Ave | Sunset Ave |  |
Sunset Ave |
| 9.35 | Prospect Ave | Verona Twp, Essex Co West Orange Twp, Essex Co |
||
| 8.65 | Prospect Ave | Woodland Ave | |
|
| 8.34 | Prospect Ave | Shopping center entrance | |
|
| 8.11 | Prospect Ave |  Eagle Rock Ave |
|
Eagle Rock Ave |
| 7.92 | Prospect Ave | Harrington Ave | |
Plant entrance |
| 7.78 | Prospect Ave | Crystal Ave | |
|
| 7.64 | Prospect Ave |  |
overpass | |
| 7.54 | Prospect Ave | overpass | Ramp from south to east |
|
| 7.29 | Prospect Ave | Shopping center entrance | |
Private road |
| 7.18 | Prospect Ave | Rodney Cir | |
|
| 6.67 | Prospect Ave Mount Pleasant Ave |
 Mount Pleasant Ave Prospect Ave |
|
|
| 6.36 | Gregory Ave | |
 Mount Pleasant Ave |
|
| 5.93 | Gregory Ave |  Northfield Ave |
|
Northfield Ave |
| 5.61 | Gregory Ave | Gregory Pl | |
Mitchell St |
| 5.34 | Gregory Ave | Forest Hill Rd | |
Forest Hill Rd |
| 5.01 | Gregory Ave | Walker Rd | |
Walker Rd |
| 4.67 | |
West Orange Twp, Essex Co South Orange Village Twp, Essex Co |
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| 3.64 | Wyoming Ave | |
South Orange Ave |
|
| 3.53 | Wyoming Ave | South Orange Ave |
|
|
| 3.31 | Wyoming Ave | South Orange Village Twp, Essex Co Maplewood Twp, Essex Co |
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| 2.29 | Wyoming Ave | Maplewood Twp, Essex Co Millburn Twp, Essex Co |
||
| 1.57 | Wyoming Ave | Glen Ave | |
Glen Ave |
| 1.53 | Wyoming Ave | Lackawanna Railroad | overpass | Lackawanna Railroad |
| 1.43 | Wyoming Ave Millburn Ave |
|
 Millburn AveWyoming Ave |
|
| 1.23 | Millburn Ave | Essex St | |
|
| 1.03 | Essex St | Millburn Ave | Lackawanna Pl | northbound |
|
| 0.95 | Essex St | Millburn Ave | Elizabeth River | bridge | Elizabeth River |
| 0.92 | Essex St | Millburn Ave Main St |
 Short Hills RdEssex St | Millburn Ave |
|
|
| 0.92 | Main St | Essex Co jurisdiction Municipal jurisdiction |
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| 0.68 | Main St | Long Ave | |
Long Ave |
| 0.47 | Main St | Willow St | |
Willow St |
| 0.25 | Main St | Millburn Twp, Essex Co Springfield Twp, Union Co |
||
| 0.18 | Main St |  |
overpass | |
| 0.00 | Main St |  Springfield Ave |
|
Springfield Ave |
| 0.00 | Southern terminus of , Springfield Twp, Union Co |
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