Four young women from Mahtomedi and St. Paul have undertaken a journey of enlightenment — by bicycle.

They're on a quest to learn all they can about threats to public lands, crossing the nation from coast to coast on a 4,871-mile expedition that will end in South Carolina in December.

"We have a very big and fascinating country," said Hannah Scout Field, of Mahtomedi. "It's amazing how much you can learn about meeting people and seeing places and experiencing how generous every part of the country is."

Field and two of her 2013 classmates from Mahtomedi High School, Alex Benjamin and Katie Ledermann, have shared their enthusiasm for the outdoors since they met as sophomores. Now they've joined their friend Ariana Amini, of St. Paul, for what they call "Women on Wheels for Wild Lands," a three-month tour of the southern United States.

"It feels good to be doing this trip for something beyond ourselves," Benjamin said recently during a two-day layover in Austin, Texas.

The women, all of them now 22, mapped their journey well in advance, calculating distances and arranging learning opportunities and personal encounters at every stop. They try to bike 80 miles a day even as they stop to explore federal and state lands, including parks.

Many people know that political decisions can shrink or restrict public lands, but the women are learning that other threats are looming as well. Among them, Field and Benjamin named climate change, over-visitation, invasive species, land transfers and small park budgets.

"I don't think the average American is concerned. The most dangerous mentality is taking our lands for granted. We think they're here forever, they're never going away, and that's not the case," said Benjamin, a chemical engineering graduate of Montana State University in Bozeman.

The federal government owns about 640 million acres of land, according to the Congressional Research Service. Four major agencies manage most of it: the Bureau of Land Management, National Park Service, Fish and Wildlife Service and Forest Service. The Department of Defense administers an additional 11.4 million acres for military bases and training ranges.

The states own another 197 million acres, with more than half of that acreage in Alaska.

The Minnesota women — now accompanied on their journey by "honorary woman" Peter Kvale, 23, of Duluth — have been interviewing everybody from private citizens to park managers and city officials along the way. They've blogged their day-to-day discoveries on their website, illustrating their stories with photographs of places they've explored.

"There's a lot to process. Every day comes with new experiences," said Field, a Macalester College graduate who majored in applied mathematics.

Ledermann graduated from the University of Minnesota-Morris in environmental studies and financial and organizational management, and Amini graduated from Macalester in biology and religious studies.

Once the four women finish their trip and return to Minnesota, they plan to share what they've learned in speaking engagements and possibly a documentary, even a children's book.

"We want to create something comprehensive and tell our story," Benjamin said.

The travelers carry all their gear on their bicycles, and have no supply vehicle to accompany them. They've experienced several flat tires and many drivers passing much too close, but they said they're setting an example for other women.

"Women are capable of doing everything they want to do," Field said. "We're telling people that traveling by bicycle is fine, especially women — they're empowered."

Do their parents approve? Leann Benjamin of White Bear Lake, Alex's mother, certainly does.

"There would be no way they shouldn't have done this," said Benjamin. "In this turbulent time in this world, with so much negative media and press, these girls have found nothing but generosity and kindness in the world."

On behalf of all the parents, she said, "We are unbelievably proud of our girls."

Kevin Giles • 651-925-5037