PORTLAND — When Dr. Harold Osher purchased his first map in 1975 on a trip to London he didn’t know he would eventually end up with one of the most valuable map collections in the world.

Now, Osher, 94, has decided to donate the remainder of his rare and historic maps and create a significant new endowment in order to further the mission of the Osher Map Library & Smith Center for Cartographic Education at the University of Southern Maine. Described as a “transformative philanthropic gift,” the joint contributions represent the largest gift in USM’s history, according to a press release.

As a result of the monetary gift, a new USM-Osher Map Library Foundation will be established to help oversee and deepen the reach of the library’s expanded permanent collection and its educational mission, the university said at a press conference held June 22.

USM originally opened the Osher Map Library in 1994, after receiving an initial gift from Osher and his wife, Peggy, several years earlier.

With this new donation, the map library will not only be able to maintain, but expand its reputation as one of the most “dynamic and innovative educational resources” for cartographic research and scholarship in the world, the USM press release said.

Glenn Cummings, president of USM, called the maps now available through the Osher Map Library an “important and invaluable collection” and said Osher’s latest gift would take the library “to a new level.”

This gift “will not only tremendously benefit our university, our communities, and scholars worldwide, but also serve as a lasting legacy of (the Oshers’) extraordinary philanthropy and devotion to the people of Portland and the state of Maine,” Cummings said.

Along with gifts from other collectors, the Osher Map Library has grown to encompass 60 separate collections, including “exceptionally rare globes and more than 450,000 maps and historic artifacts,” which together value in excess of $100 million, according to Osher family spokesman Glenn Parkinson.

Parkinson said Osher “does nothing halfway” and it didn’t take long after that first purchase for his map collection to become “one of the most significant in private hands.”

But, he said, “the real value” of Osher’s latest gift is in education and research and making the Osher Map Library “a library of real distinction and real value to researchers and historians.” With the new endowment, Parkinson said, the Osher Map Library would become “a leader in using maps as powerful teaching tools.”

Matthew Edney, USM’s Osher Professor in the History of Cartography, agreed, saying, “maps aren’t just fun, they’re amazing tools for looking at all sorts of things” from politics to sociology and literature to economics. All of these areas of study are informed by maps, he said.

Edney said Osher has “always had a discerning eye and always held out for the best,” which is what makes “it such a joy to handle this collection.”

Among the “precious rarities” in Osher’s collection are a 1475 map of the Holy Land, including illustrated Biblical scenes, the “Leo Belgicus,” or Lion of the Netherlands map, circa 1617, and John Mitchell’s map of the British Colonies in America from 1755, often called “the most important map in American history,” the USM press release said.

The first map, purchased more than 40 years ago, though, was one of the state of Maine created by J. H. Colton, a leading map publisher in New York, and was originally part of Colton’s 1866 atlas. The Colton map cost Osher and his wife five pounds and is now worth much more.

Libby Bischof, a history professor and director of the Center for Collaboration and Development at USM, said what sets the Osher Map Library apart is that it’s “inclusive, hands-on and high impact,” especially for the more than 3,000 K-12 students from Maine that visit the library each year.

She said the map library is often “a hub of activity” with scholars, researchers and others all “telling of their discoveries, talking and asking questions. A map allows us to understand our own history and our own stories.”

And Bischof agreed with Edney, that the map library attracts more than those interested in cartography. She said creative writers, engineers and printmakers all make it a point to visit and get a look at the vast collection.

“The curricula possibilities are really endless,” she added of the educational benefits offered by the map library.

And while Osher recognizes that maps can be “ideal teaching tools and primary sources of information,” his motive originally was simple. “I started collecting maps because I love them,” he said.

In praising Osher and his late wife for their continued support of the map library, Cummings said they could have given their collection to any institution in the world.

“The Smithsonian would love to get their hands on it,” but, he said, Osher “loves Portland and is committed to its future.”

Kate Irish Collins can be reached at 710-2336 or kcollins@theforecaster.net. Follow Kate on Twitter: @KIrishCollins.

Glenn Cummings, left, president of the University of Southern Maine, and Dr. Harold Osher sign an agreement June 22 that creates a significant new endowment for the Osher Map Library & Smith Center for Cartographic Education.

With Dr. Harold Osher looking on, Glenn Parkinson, a family spokesman, announces that Osher will leave the remainder of his valuable map collection to the Osher Map Library at USM. Parkinson said the gift would make the library one “of distinction.”

Colton’s Map of Maine was the first map Dr. Harold Osher purchased. He bought it for five pounds on a trip to London in 1975.