The U.S. was once covered in around 1 billion acres of forest. While much of that land has been developed, a recent study led by the Nature Conservancy found that there are still as many as 127 million acres of former forestland in the lower 48 states—an area about twice the size of Oregon—that could feasibly be reforested. In that space, we could plant 68 billion trees, which could capture more than 300 million metric tons of carbon dioxide every year, roughly as much as the pollution from 67 million cars.
A new tool based on the study, called the Reforestation Hub, maps out exactly where reforestation could happen in each state, county by county. The map, created by the Nature Conservancy and American Forests, doesn’t include most urban land or farmland, or areas that were originally different types of ecosystems, such as grasslands. But in a variety of other areas—including pastures, some protected federal land, places that burned in wildfires or that flood frequently, and some urban spaces, like grass-covered parks or concrete schoolyards—there’s an opportunity to bring back trees.
Some of the largest opportunities are in the Midwest and Southeast. Missouri, for example, has 8.7 million acres that could potentially be reforested, and Kentucky has nearly 6 million. Both states have large amounts of pasture, some of which could be put to different use if consumers buy less meat and dairy, if meat production becomes more efficient, or if more trees can be added into current pasture. Kentucky’s aptly named Barren County, for example, has around 146,000 acres of pasture that could be reforested, capturing around 237,000 metric tons of CO2 each year.
There are opportunities throughout the country, and opportunities for multiple benefits. In cities, as trees capture carbon, they also improve air quality, reduce heat on hot days, and improve mental health. In watersheds, trees improve water quality by acting as natural filters.
In some cases, forests can regrow naturally. But in many areas, they’ll need extra help. In Paradise, California, devastating wildfires burned so intensely that they destroyed the seeds that would normally germinate after a fire; American Forests is working with groups in the area to replant trees (and is also planting strategically to help the forest better adapt to climate change and future fires). Funding is also an issue. On federal lands, the U.S. Forest Service estimates that it has the resources to restore forests on only 20% of the land area that could potentially be reforested.
The new map—the most detailed look to date at where reforestation could happen in the U.S., which will continue to be updated with new data—is something that conservation organizations and other nonprofits, foresters, and property owners can use to plan new tree-planting locally, and that the government could use to plan new policy and allocate funds to support mass reforestation.