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During the winter of 2013, the number of eastern monarch butterflies sank to their lowest level on record after years of decline. Other pollinators, like honeybees, were also struggling.
In response, the Obama administration formed a task force to figure out how to reverse these trends. Orley “Chip” Taylor, the founding director of Monarch Watch at the University of Kansas, was invited to speak at a meeting in D.C. with highway managers.
“In that talk, I presented an idea that we could improve monarch habitat by creating strips of milkweed and native plant habitat along the banks of the interstate highways, especially along I-35,” Taylor said.
Interstate 35 is a major corridor in the U.S., stretching from Laredo, Texas, to Duluth, Minnesota. It also runs through the heart of the eastern monarch butterfly’s multi-generation migration route from the northern U.S. and southern Canada to the high-elevation fir forests of central Mexico.
Taylor’s idea of returning stretches of roadsides to milkweed and other native wildflowers was called the “Monarch Highway.” The multi-year proposal aimed to offset habitat loss, which Taylor said has been a primary driver of the pollinator’s decline in recent decades.
“If you look at the interstates, it’s possible to put in a lot of habitats 100 feet or more away from the interstate traffic, and those were our targets,” he said.
The White House included the Monarch Highway in a national pollinator plan released in 2016. And the Federal Highway Administration signed a memorandum of understanding with the six state departments of transportation that manage I-35 – Texas, Oklahoma, Kansas, Missouri, Iowa and Minnesota. The partners even released a logo.
But the Monarch Highway lost momentum, Taylor said. One reason was financial. The state departments of transportation didn’t receive additional federal funding to implement the plan.
Another challenge was that the priorities of the state and federal agencies often changed with new leadership, Taylor said. In some situations, decision-makers at the top were supportive, but people who mowed the roadsides were unaware of the policy changes or didn’t adhere to them.
“All of these things take money, and they take personnel, and they take knowledge, and to a certain extent, they take training,” Taylor said. “So getting these things started is not easy. Maintaining them is hard.”
Even though the 1,568-mile long project stalled, some states have embraced creating butterfly rest stops along roads.
Experts say adding areas where monarchs can eat, rest and lay their eggs, gives them a greater chance of completing their migration amid large-scale habitat loss – especially in states like Iowa and Illinois, where less than 0.1% of original prairie remains.
Growing interest in pollinator rest stops
In Missouri, the Highway 13 Butterfly Trail stretches 300 miles.
Started by residents in the town of Hamilton in 2017, the project aims to add butterfly habitat along roadsides and in parks and public spaces within roughly 13 miles on either side of the highway. Many of the partners involved also view it as a way to boost tourism along the route.
In Illinois, where the official state insect is the monarch butterfly, local governments, conservation groups and state agencies are working on a similar concept called the Route 66 Monarch Flyway.
The historic route between Chicago and St. Louis is one of the monarch butterfly’s main migration pathways in Illinois, said Susan Helm, co-president of the project.
A large part of her role is helping groups that want to add pollinator gardens within the 66-mile wide corridor.
“[These projects] tend to fail when the right things aren't done from the very beginning, from site prep to whether you use seeds or plugs … and then the maintenance along the way,” Helm said. “There is no such thing as a no maintenance garden, and that includes a pollinator supporting garden.”
Interest in the Route 66 Monarch Flyway has “snowballed,” she said.
“There's a lot of enthusiasm, whether it's a library, a park, even businesses, historic sites, or Lincoln's home, Oakridge Cemetery, where Lincoln's buried,” Helm said.
Monarch butterflies are good ambassadors for other species, like native bumblebees, she added.
“In helping monarchs, we're helping all pollinators,” Helm said.
A key partner for the Route 66 Monarch Flyway is the Illinois Department of Transportation.
Scott Hall, Illinois DOT roadside maintenance manager, said the agency issues some permits for conservation groups to establish and manage roadside pollinator habitat. But Illinois DOT does much of this work along Route 66 and across the state.
Hall recently worked with researchers at the University of Illinois Urbana-Champaign to identify seed mixes that benefit pollinators and thrive in the state’s roadsides.
“We have planted a bunch of native seed,” Hall said. “We have also found that just by changing our mowing practice and letting things come back naturally, the seed bank is already there.”
The agency follows the Illinois Monarch Project mowing guidelines to reduce habitat disturbances, especially during the eastern monarch butterfly’s peak migrations. That includes leaving two-thirds of the vegetation in a right-of-way in any given year and limiting mowing to specific windows from July to mid-August and after Sept. 30.
“When [the monarchs] are heading back south, we pause our operation, and then we get started up in October,” said James Schackmann, an Illinois DOT maintenance resource specialist.
There are some exceptions for invasive brush, potential safety issues and construction, Schackmann said. But reduced mowing helps monarchs and other pollinators while also cutting costs in fuel, labor and equipment wear and tear.
‘It's part of our landscape’
Purple and yellow blooms wave in the breeze near an I-35 exit in Ames, Iowa, on a recent summer day.
Iowa has long been a leader in returning roadsides to native plants, although monarch conservation wasn’t at the forefront of that change.
Decades ago, this area likely would have been covered with bromegrass from Eurasia. The state planted non-native grass seed, mowed from “fence to fence” and blanket sprayed herbicide across the entire right of way to control weeds, according to Rachel Harris. She’s the chief landscape architect in roadside development for the Iowa DOT.
But the 1970s gas crisis pushed the Iowa DOT to experiment with a new approach to roadside management, Harris said. By 1988, lawmakers had enshrined efforts to include native grasses and wildflowers and cut back on mowing and spraying in state code.
“The less amount of time we can spend on the side of the road mowing and putting down chemicals is better in our opinion – from a cost standpoint and also from an environmental standpoint,” Harris said. “So, it’s kind of a win-win situation.”
Native prairie plants are also better adapted to the local climate and soil conditions compared to many non-native species and stabilize roadsides with their massive roots, she said. Harris estimates the Iowa DOT has seeded between 500 and 750 acres with natives per year since 2020 through erosion control plans, which she said are required for road projects.
Cities and counties across the state have adopted similar practices. To date, more than 50,000 acres of roadsides in Iowa have been planted with prairie grasses and wildflowers.
Native plants in roadsides also provide critical habitat and corridors in a state considered the most biologically altered in the U.S. Historically, tallgrass prairie covered 70-80% of the state. Today, around 85% of the landscape is used for agriculture, primarily corn and soybeans.
“For biodiversity and for a lot of insects and small birds and small mammals, that connected corridor habit is so important for allowing them to travel between larger patches of habitat,” Harris said.
Another benefit is aesthetics. While reconstructed prairies can take several years to establish, Harris said the Iowa DOT receives emails from drivers expressing their appreciation for the ever-changing colors and textures across the seasons.
“That beauty is part of Iowa, and it's part of our landscape," Harris said. "We're really proud to be able to provide that for people as they travel across the state."
Near the I-35 exit north of Ames, Harris watches a tiny Eastern Tailed-Blue Butterfly flirt with purple prairie clover and bumblebees swarm fragrant beebalm blossoms.
On cue, a monarch butterfly flies overhead.
This story was produced in partnership with Harvest Public Media, a collaboration of public media newsrooms in the Midwest and Great Plains. It reports on food systems, agriculture and rural issues.
