Once there were nine large numbered fieldstones, sunk in 1841, to mark a new boundary between Baltimore County and then 4-year-old Carroll County.
Now there are three - and one is 60 to 70 feet out of line.
The question about the boundary came up last year after a survey for a proposed development near Hampstead that would straddle the border at Trenton Mill Road and Route 30. The survey seemed to put the property too far into Baltimore County.
So officials from both counties put their surveyors in the field to re-mark this longest section of the 163-year-old border, said Steven D. Powell, the Carroll commissioners' chief of staff.
The surveyors will compare notes to draw a new line, he said. The new border will have to be approved by both county governments and the General Assembly.
By the 1841 survey, a straight 16 1/4 -mile section of the line runs 17 degrees northeast, beginning at a point on a 19th-century bridge over the North Branch of the Patapsco River - and intersects the Mason-Dixon Line at the Pennsylvania border, said Richard S. Krebs, Carroll County's surveyor.
But the old Westminster Turnpike bridge is now part of Liberty Reservoir - and that's a problem, said Krebs and his Baltimore County counterpart, Patrick A. Simon, chief of surveys in the Department of Public Works.
The stone bridge is overgrown and partially buried in sediment, said Simon, an old-bridge enthusiast who plans to excavate it. If an 1806 date in the Baltimore County Historical Society records is correct, he said, it could be the oldest stone bridge in Maryland.
Powell and the surveyors said the starting point for the boundary is crucial.
For the developer, having land several hundred feet into Baltimore County rather than the more developed northeast corner of Carroll would reduce the possible housing density.
"We're just trying to go through and figure out where this line really is. We have to resurvey the line, as we understand it, and get the General Assembly to approve it," Powell said. "Both counties are working together on this - and working well."
The Carroll County work should be completed in about a month, Krebs said, but Simon said the Baltimore County work would take a year or more, including excavating the bridge.
In the field last week, Krebs and Global Positioning System technician Stephen Cornwell hacked a path through the woods at the edge of a field on the borderline near Falls Road and Indian Run. A fieldstone 14 inches wide by 18 inches high bears the number 6, carved into it more than 160 years ago.
"The only reason it was saved is because it's back in the woods," Krebs said.
The two other surviving boundary stones are No. 2, about four miles up from the bridge, east of Route 91, and No. 3, just south of Route 30.
The stones were set in 1841 at two-mile intervals, Krebs and Simon said. There was a record of No. 4 about 25 years ago still in place by Black Rock Road.
As for the rest, Krebs said, "they were just in fields, and may have been gone in the 1860s."
Even if one of the stones were to be reported now, Simon said, it would be limited to historical interest, as its position would be suspect and of no use for the survey.
The most important of the vanished stones is No. 9, which marked the intersection with the Mason-Dixon Line, Simon said.
"There is no Mason-Dixon stone," Krebs said. "That's what caused the whole problem. In the old deed of 1841, it says, 16 1/4 miles to intersect the Mason-Dixon Line. ... If there had been one, we would not be out here today."
Preliminarily, Simon said, "if a line were drawn between stones No. 2 and 6, then No. 3 is about 60 feet off the straight line. ... That's assuming 2 and 6 are right. The difference would be 67.59 feet - but the bridge would be 370 feet out."
The surveyors have to determine where to start drawing the new line on the bridge.
A 20-foot difference on the bridge could mean a 370-foot difference at the Mason-Dixon Line, Krebs said. "That's why it's critical to figure it out," he said.
A volunteer project by the Carroll chapter of the Maryland Society of Surveyors also has contributed to drawing the new line, Krebs and Simon said. The volunteers dug through 6 to 8 inches of sediment to mark a possible point on the southwest corner of the bridge.
Survey deeds and old photographs "indicate a starting point at the southwest corner of the main arch, but you cannot see any arch," Simon said. A photograph of the old bridge shows three arches, but only the top of one is visible on the north side.
"I'd like to excavate the south side of bridge," he said. "You can just see the top four or five feet. It looks like the whole deck. I hope the arches are there."
Krebs said this is one of the most interesting jobs he has had in 30 years of surveying.
Of the outcome, Powell said: "If you always thought you lived in Carroll County, we'd like you to live in Carroll County, and if you always thought you lived in Baltimore County, we'd like you to be in Baltimore County - unless they're trying to take the line all the way to Hunt Valley."