PERRY, Maine — A rough-cut, red granite stone that marks the 45th parallel — that imaginary line around the Earth that is halfway between the equator and the North Pole — was recognized Saturday with an interpretive panel that explains its history.

The panel notes that Perry is at the same latitude as the French wine regions of Bordeaux, the deserts of Mongolia, the northernmost tip of Japan and Salem, Ore.

On Saturday, state Sen. Kevin Raye, R-Perry, Rep. Anne Perry, D-Calais and members of the Board of Selectmen, Perry Improvement Association, the Border Historical Society and St. Croix Historical Society, among others, stood on the side of Route 1 in an area known locally as Back District Road for the unveiling of the impressive panel.

Around 1883, U.S. Coast Survey topographers Charles Meigs Bache and Alexander Wadsworth Longfellow — the brother of poet Henry Wadsworth Longfellow — were in Perry conducting a survey of the coastline. They used a device called a plane table, a primitive survey tool by today’s standards.

Bache and Longfellow noticed that a Perry house with a red door chimney fell nearly on the 45th parallel, missing by only a few tenths of a second. On their own time, the two decided to mark the exact 45th parallel, which was very likely near Shore Road, with a brass pin, Henry E. Nelson, senior geodesist for the Maine Department of Transportation, said in prepared notes.

“The current location of the stone is not exactly on the 45th parallel for a couple of reasons,” Nelson added. “For one, the precision of the brass pin was lost when the current location was laid out. Also, advances in the mathematical models of the shape of the Earth have improved as satellite technology entered the surveying realm.”

According to Nelson, the actual 45th parallel as defined in today’s terms is only a “stone’s throw” from the monument. “This is why if you pass by the location with a GPS navigator on your dashboard, it will report the 45th parallel a little north along Route 1 from the monument,” he added.

The interpretive plaque unveiled Saturday compares the then state-of-the-art surveying of the past with the surveying of today with its high-tech computers and satellites.

“In the 1800s method of surveying it took years to bring in triangulation control, do the mapping and create the charts,” Nelson said. “Today, the survey crew can take the topography in the morning and view it on a laptop computer in the survey van at noon, and after a few days of editing, can create a plot to be delivered to the Maine DOT designers.”

On Saturday, Raye told the handful of people at the dedication ceremony that soon after he was elected to the Maine Senate in 2004 he pushed to have Route 1 in Perry and Robbinston rebuilt. Members of the Perry Improvement Association recognizing the marker’s historical and geographic significance, as well as its value as a tourist stop, asked Raye to preserve the site when the road was rebuilt.

Raye appealed to Commissioner David Cole of the Maine DOT, and the site was saved and improved upon. DOT senior landscape architect Larry Johannesman and his staff designed the new historic site, all funded by the DOT.

Nancy Montgomery, a Portland-based graphic designer, designed the interpretive panel with the help of Perry residents.

Picnic tables surround the marker and there is a black-topped pull-off area.

Reading from the Perry Sesquicentennial 1818-1968 Historical Souvenir Book, Raye said Bache and Wadsworth were proud of their work. The original brass marker placed by Bache and Wadsworth lasted about eight years.

Fearful that the marker might be lost, Perry residents decided to place a more permanent marker, and in 1896, a red granite stone was ordered at a cost of $8.

The stone was not laid until 1899, when another Perry resident brought the matter of the granite marker to the town’s attention.

“Transportation was no mean consideration when moving the stone,” the historical book said. “Six cubic feet of close-grained granite weighed more than half a ton. The only conveyance deemed suitable with the time was [a local man’s] hayrack, heavily bedded with hay,” the historical book said. The stone was set on July Fourth.

David Turner, chairman of the Board of Selectmen, said Saturday he was pleased with the attention the site was receiving.

“This is Perry’s claim to fame and it is our only rest area and we want to keep it,” he said.

Turner noted that tourists visited the site this summer.