Historian Dewey Livingston first became aware of the mysterious “Grippi Tube 18” map after reading a book by his predecessor, Jack Mason, over 30 years ago. Mr. Mason mentioned it in a footnote while discussing Charles Webb Howard’s desire to split up the ranches on the Point Reyes Peninsula, but the whereabouts of the 1879 map were uncertain. The only clue was the name of a land surveyor who once owned it: Joseph Grippi. 

The crinkled, yellowish map remained untouched for years—until last month, when Mr. Livingston uncovered it while analyzing thousands of historic survey maps acquired by the county in 2015. 

Mr. Livingston has been working with the Marin County Free Library since April 2016 to archive over 30,000 maps, surveys, subdivision plans, field notes, work ledgers and indexes purchased from a land surveyor. He assesses the trove piece by piece in the order that the library received them, but last month, it dawned on him to peruse the cardboard tubes for the bygone artifact. He was stunned when he found number 18.

“It was almost ceremonial,” he said of the moment when he and a fellow researcher began unfurling the map. 

True to legend, “Grippi Tube 18” contained a map of the peninsula from 1879. It features detailed drawings on linen of Charles Webb Howard’s ranches, with precise locations of buildings and auxiliary trails—and dozens of springs sprinkled across the Point. 

“Water is a big deal in subdivisions,” Mr. Livingston said. “This helps me and other historians, and would be of interest for hydrologists, geologists, archeologists and park planners.”

Mr. Livingston has studied West Marin’s past since knocking on Mr. Mason’s door in 1984 and has written numerous authoritative histories on the Point Reyes National Seashore and other national parks, including the Channel Islands and Death Valley. He calls the Grippi map the “pièce de résistance,” the crown jewel of a collection that offers a new lens through which to interpret history. 

One map shows the names of houses and hotels of Muldrow City, a never-completed community on the east shore of Tomales Bay. An 1869 survey map of the area now called Bear Valley helped settle a suspicion he’s had for decades, related to the first Mexican land grantee on Point Reyes. In the 1970s, a park service group had claimed that Rafael Garcia’s adobe house was located near the Olema marsh. But Mr. Livingston believed it was where the Red Barn stands, at seashore headquarters, and the map confirmed his theory.

It was this cultural and historical significance that persuaded the county to acquire the collection in 2015. That September, the Board of Supervisors voted to add $45,000 to a $15,000 grant from the Marin Chapter of the California Land Surveyors Association for the archive project.

“When I first saw it, I was so blown away,” Laurie Thompson, the librarian who oversees the collection, said. “I couldn’t believe that in our own backyard there was this virtual time capsule of Marin County maps that had been in private hands for 150 years. It was important to get something like that in the public domain.”

Since the mid-19th century, the collection snowballed as it passed through generations of land surveyors, many of whom held the office of county surveyor. Hiram Austin was the earliest in a line that included George Dodge, George Richardson and J.C. Oglesby. The collection’s value grew with scores of survey journals and field notes, information that had never been recorded or made publically available. The last in the chain of land surveyors was Bill Schroeder, who obtained the collection in the 1980s. 

After holding onto it for 27 years, Mr. Schroeder decided to offer the collection to the county upon his retirement.

“I do feel that public ownership of this is in the best interest of everybody,” he told the board in 2015. “They’re kind of like the old-growth redwood: when they’re gone, they’re gone.”

Mr. Livingston is now leading a tiny volunteer team tasked with cataloging the maps inside an annex of the Anne T. Kent California Room at the Marin County Civic Center. (He helped design the annex’s layout, and laughs in agreement that he “surveyed the survey room.”) Maps that have been assessed are stored in drawers along the edge of the room and, if it takes 451 degrees to burn a book, it takes a cool 62 degrees to preserve a fragile map.

The collection dates back to 1849, but the bulk of it spans the late 19th century through the 1970s. Though its components have potential uses for various professionals, the one group that stands to benefit the most is modern-day land surveyors seeking original property lines to help settle neighbor disputes or assist in subdivisions. 

Only licensed surveyors and serious researchers are allowed to view the collection, and only by appointment. Last Thursday was a busy afternoon: nine surveyors came in with assessor’s parcel numbers and the hope that their parcel was included in the mix. (Even though there are thousands of maps, not every parcel is covered in the collection.) 

Mr. Livingston is digitizing the maps with the intent of posting them to the library’s website sometime next year. He is also looking into raising funds to purchase a high-quality photo scanner for some of the larger maps, as well as other preservation materials. 

Ms. Thompson said there’s a “lifetime of work ahead,” but said they’ve struck gold with Mr. Livingston.

“I thought, ‘Who would be the perfect person?’ and there was no hesitation,” she said. 

For Mr. Livingston, the project both brings weekly discoveries and fulfills a lifelong aspiration. 

“Since I was a teenager, I’ve wanted to work for the Marin County Library,” he said. “I’d look at the Civic Center thinking, ‘Oh man, I want to work there.’”