- Southern Terminus:
- Deer Park Avenue (NY 231) in North Babylon
- Northern Terminus:
- Huntington-Smithtown town line
- 7.56 miles
Commack Road is a north/south route in western Suffolk. It begins at Deer Park Avenue (NY 231) in North Babylon and runs north to Jericho Turnpike (NY 25) in Commack. It is a two- to four-lane road with traffic lights. Some portions are divided. North of Jericho Turnpike (NY 25), Commack Road changes names to become Town Line Road. It runs north a few blocks to the Huntington-Smithtown town line, where CR 4 ends. Town Line Road continues north as a two-lane local street. CR 4 was planned to extend further north along Town Line Road and Bread and Cheese Hollow Road to Fort Salonga Road (NY 25A) in Fort Salonga, but this section was never taken over by the county.