- Southern Terminus:
- Montauk Highway (CR 80) in Westhampton Beach
- Northern Terminus:
- Quogue-Riverhead Road (CR 104) in Flanders
- 4.01 miles
Old Riverhead Road is a north/south route connecting Westhampton Beach to Riverhead. Oak Street becomes Old Riverhead Road upon crossing Montauk Highway (CR 80). It runs north past Gabreski Airport to an interchange with Sunrise Highway (NY 27). Then, it curves to the northeast and ends at a traffic circle at Quogue-Riverhead Road (CR 104), which continues north to Riverhead. The entire length is a two-lane undivided road, except in the area of the interchange with Sunrise Highway (NY 27), where it widens to four lanes and has a median.