Note on Suffolk County Routes: This list contains the county route numbers and termini of roads maintained by Suffolk County and recognized as county routes by the state. There also other roads that were assigned county route numbers but never actually taken over by the county. These numbers can be found in a document available in the document library section of this web site.
 | County Line Road |
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Direction: North/South Southern Terminus: Montauk Highway (NY 27A) in Amityville Northern Terminus: North of Joyce Avenue in Amityville Distance: 1.54 miles Signed: Yes | |
 | Dixon Avenue, Straight Path, Seamans Neck Road |
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Direction: North/South Southern Terminus: Broadway (NY 110) in Amityville Northern Terminus: Deer Park Road (NY 231) in Dix Hills Distance: 8.65 miles Signed: Yes | |
 | Wellwood Avenue, Pinelawn Road |
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Direction: North/South Southern Terminus: New York Avenue in Lindenhurst Northern Terminus: Walt Whitman Road in Melville Distance: 7.18 miles Signed: Yes | |
 | Commack Road, Town Line Road |
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Direction: North/South Southern Terminus: Deer Park Avenue (NY 231) in North Babylon Northern Terminus: Huntington-Smithtown town line Distance: 7.56 miles Signed: Yes | |
 | Kings Highway, Rabro Drive |
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Direction: East/West Western Terminus: Old Willets Path (CR 108) in Hauppauge Eastern Terminus: Hauppauge Road (NY 111) in Hauppauge Distance: 0.86 miles Signed: Yes | |
 | Wicks Road |
|
Direction: North/South Southern Terminus: Crooked Hill Road (CR 13) in Brentwood Northern Terminus: Vanderbilt Parkway (CR 67) in Brentwood Distance: 1.70 miles Signed: Yes | |
 | Elwood Road |
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Direction: North/South Southern Terminus: Jericho Turnpike (NY 25) in Elwood Northern Terminus: Fort Salogna Road (NY 25A) in Northport Distance: 3.94 miles Signed: Yes | |
 | Woodbury Road, Pulaski Road, East Northport Road |
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Direction: East/West Western Terminus: Harbor Road (NY 108) and Woodbury Road (Nassau CR 12) at the Nassau-Suffolk border in Cold Spring Harbor Eastern Terminus: Main Street (NY 25A) in Kings Park Distance: 11.16 miles Signed: Yes | |
 | Oak Street, Hoffman Avenue, Railroad Avenue |
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Direction: East/West Western Terminus: Old Sunrise Highway and County Line Road (CR 1) at the Nassau-Suffolk border Eastern Terminus: Great East Neck Road (CR 96) and Trolley Line Road in Babylon Distance: 4.42 miles Signed: Yes | |
 | Fifth Avenue, Wicks Road, Crooked Hill Road |
|
Direction: North/South Southern Terminus: Montauk Highway (NY 27A) in Bay Shore Northern Terminus: Commack Road (CR 4) in Brentwood Distance: 7.58 miles Signed: Yes | |
 | Clinton Avenue |
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Direction: South ONLY Southern Terminus: Montauk Highway (NY 27A) in Bay Shore Northern Terminus: Fifth Avenue (CR 13) in Bay Shore Distance: 0.64 miles | |
 | Indian Head Road |
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Direction: North/South Southern Terminus: Jericho Turnpike (NY 25) in Commack Northern Terminus: Main Street (NY 25A) in Kings Park Distance: 3.21 miles Signed: Yes | |
 | Terry Road, Smithtown Boulevard, Lake Shore Road, Portion Road, Horse Block Road |
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Direction: East/West Western Terminus: Middle Country Road (NY 25) in Smithtown Eastern Terminus: Montauk Highway (CR 80) in Brookhaven Distance: 16.60 miles Signed: Yes | |
 | Carleton Avenue, Wheeler Road |
|
Direction: North/South Southern Terminus: Montauk Highway (NY 27A) in East Islip Northern Terminus: Joshua's Path (NY 111) in Hauppauge Distance: 5.51 miles Signed: Yes | |
 | West Avenue, Lake Street, Waverly Avenue, Patchogue-Holbrook Road |
|
Direction: North/South Southern Terminus: Division Street (CR 65) in Patchogue Northern Terminus: Portion Road (CR 16) in Lake Ronkonkoma Distance: 6.72 miles Signed: Yes | |
 | Yaphank Avenue, Main Street, Yaphank-Middle Island Road, Rocky Point Road |
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Direction: North/South Southern Terminus: Montauk Highway (CR 80) in Brookhaven Northern Terminus: NY 25A in Rocky Point Distance: 11.75 miles Signed: Yes | |
 | New Highway |
|
Direction: North/South Southern Terminus: Sunrise Highway (NY 27) in Copiague Northern Terminus: Babylon-Farmingdale Road (NY 109) Distance: 2.22 miles Signed: Yes | |
 | Old Riverhead Road |
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Direction: North/South Southern Terminus: Montauk Highway (CR 80) in Westhampton Northern Terminus: Quogue-Riverhead Road (CR 104) in Riverhead Distance: 4.01 miles Signed: Yes | |
 | Lighthouse Road |
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Direction: North/South Southern Terminus: Dune Road Northern Terminus: Northern end of Ponquogue Bridge Distance: 0.53 miles Signed: No | |
 | Deer Park Avenue |
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Direction: North/South Southern Terminus: Village Line Road in Babylon Northern Terminus: Babylon-Northport Expressway (NY 231) in North Babylon Distance: 1.34 miles Signed: Yes | |
 | Deer Park Road, Park Avenue, Mill Dam Road |
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Direction: North/South Southern Terminus: Deer Park Road (NY 231), Northern Parkway, and East Deer Park Road (CR 66) in Dix Hills Northern Terminus: West Shore Road in Huntington Distance: 6.44 miles Signed: Yes | |
 | South Country Road |
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Direction: East/West Western Terminus: Montauk Highway (CR 80) in East Patchogue Eastern Terminus: Montauk Highway (CR 80) in Brookhaven Distance: 5.63 miles Signed: Yes | |
 | North Sea Road |
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Direction: North/South Southern Terminus: North Road (NY 27/CR 39) in Southampton Northern Terminus: Noyack Road in North Sea Distance: 2.53 miles Signed: Yes | |
 | North Road |
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Direction: East/West Western Terminus: Montauk Highway (CR 80) in Shinnecock Eastern Terminus: Flying Point Road (NY 27/CR 39A) in Southampton Distance: 6.93 miles Signed: Yes | |
 | Flying Point Road |
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Direction: East/West Western Terminus: North Road (NY 27/CR 39) in Southampton Eastern Terminus: Montauk Highway (NY 27) in Southampton Distance: 0.63 miles Signed: No | |
 | Canal Road, Old North Highway |
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Direction: East/West Western Terminus: North Road (CR 39) in Shinnecock Eastern Terminus: North Road (CR 39) in Shinnecock Distance: 0.73 miles Signed: Yes | |
 | North Main Street, Three Mile Harbor Road |
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Direction: North/South Southern Terminus: Cedar Street in East Hampton Northern Terminus: Copeces Lane in East Hampton Distance: 2.51 miles | |
 | Springs-Fireplace Road |
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Direction: North/South Southern Terminus: Three Mile Harbor Road (CR 40) in East Hampton Northern Terminus: Woodbine Drive in East Hampton Distance: 3.06 miles | |
 | Shore Road |
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Direction: East/West Eastern Terminus: West Neck Road (CR 115) on Shelter Island Western Terminus: Rocky Point Avenue on Shelter Island Distance: 1.20 miles | |
 | Northville Turnpike |
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Direction: North/South Southern Terminus: Roanoke Avenue (CR 73) in Riverhead Northern Terminus: Sound Avenue in Northville Distance: 3.42 miles Signed: Yes | |
 | William Floyd Parkway |
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Direction: North/South Southern Terminus: Fire Island Beach Road (CR 75) at Smith Point County Park Northern Terminus: NY 25A in Shoreham Distance: 13.78 miles Signed: Yes | |
 | Great Neck Road, Main Street |
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Direction: North/South Southern Terminus: Montauk Highway (NY 27A) in Copiague Northern Terminus: Nassau-Suffolk border Distance: 3.77 miles Signed: Yes | |
 | Middle Road |
|
Direction: East/West Western Terminus: Sound Avenue in Mattituck Eastern Terminus: Main Road (NY 25) in Greenport Distance: 14.21 miles Signed: Yes | |
 | Edgemere Street, Flamingo Avenue |
|
Direction: North/South Southern Terminus: Montauk Highway (NY 27) in Montauk Northern Terminus: West Lake Drive (CR 77) in Montauk Distance: 3.10 miles |
