Question: Wading River was the end of the extension just north of what state highway on Long Island?

Context articles: New York State Route 25A
The Times Beacon Record
Rocky Point (LIRR station)
Shoreham (LIRR station)
Miller Place (LIRR station)
Brookhaven State Park
County Route 46 (Suffolk County, New York)
Wading River (LIRR station)
Calverton National Cemetery
Benson House (Wading River, New York)

New York State Route 25A (NY 25A) is a state highway on Long Island in New York in the United States.
 It serves as the main east–west route for most of the North Shore of Long Island, running for 73 mi from Interstate 495 (I-495) at the Queens–Midtown Tunnel in the New York City borough of Queens to NY 25 in Calverton, Suffolk County.
 The highway is a northern alternate route of NY 25, which follows a more inland routing along Jericho Turnpike.
Times Beacon Record Newspapers is a community newspaper publisher, located in Setauket, NY, consisting of seven different weekly newspapers serving Suffolk County localities on the North Shore of Long Island spanning from the town of Huntington into Wading River.
 The current publisher is Leah S. Dunaief.
Rocky Point was a station on the Wading River Extension on the Port Jefferson Branch of the Long Island Rail Road.
 This abandoned station was just east Broadway between King Road & Prince Road, along what is now access for Long Island Power Authority power lines.
Shoreham was a station on the Wading River Extension on the Port Jefferson Branch of the Long Island Rail Road.
 This is an abandoned station just east of the intersection of North Country Road & Randall Road, along what is now access for Long Island Power Authority power lines.
Miller Place (originally Miller's Place) was a station on the Wading River Extension on the Port Jefferson Branch of the Long Island Rail Road.
 The station was just east of Sylvan Avenue just north of New York State Route 25A, along what is now access for Long Island Power Authority power lines.
Brookhaven State Park is a 1638 acre state park in Wading River, New York, approximately 74 mi east of New York City.
 Established in 1971, the park land was formerly the property of Brookhaven National Laboratory.
 Protecting a large amount of the Long Island Pine Barrens, the park also contains scattered wetlands.
County Route 46 (CR 46) is a major county road in eastern Suffolk County, New York, in the United States.
 It runs south-to-north from CR 75 in Smith Point County Park (part of the Fire Island National Seashore) to New York State Route 25A (NY 25A) near the border of Shoreham and Wading River.
 The road is known as the William Floyd Parkway along its entire length, and is named after William Floyd, a Long Island native and a signer of the United States Declaration of Independence.
 Despite its "parkway" designation within the State of New York, the road is open to commercial vehicles.
Wading River was the terminus of the abandoned Wading River Extension on the Port Jefferson Branch of the Long Island Rail Road.
 This is an abandoned station just outside south of downtown Wading River, and was located on Wading River-Manor Road (former Suffolk CR 25) north of New York State Route 25A.
Calverton National Cemetery is a United States National Cemetery in the Town of Riverhead in Suffolk County on eastern Long Island in New York.
 The cemetery's street address is in Calverton but the property is in the adjacent hamlet of Wading River.
 It encompasses 1045 acre and as of the end of 2008 had 212,000 interments.
Benson House is a three-story, red-shingled wood-frame home in Wading River, New York, situated on the North Shore of Long Island, on a 150-foot-high bluff overlooking Long Island Sound.
 From 1942 until 1945 it housed an important World War II counterintelligence operation, designed to deceive Germany and Japan about Allied war plans.