Here is a sentence that appears on a federal health website, and that gets quoted in city plans, grant applications, news stories and nonprofit fundraising appeals: only 39 percent of the US population lives within half a mile of a park.
It is a striking number. By that count, six in ten Americans have no park within half a mile of home.
It is also a number with no source. Not a thin source. Not an old source. No source at all. CDC publishes it with no citation on the page, no citation in the downloadable PDF, and a Sources link that leads to an empty spot on the same page.
That is not a scandal. It may well be right. But it points at something more useful than the statistic itself: access to a park is not a fact about the world. It is a measurement choice, different federal programs make that choice differently, and the choice moves the answer by tens of millions of people.
The most-quoted park statistic in America has no citation
The sentence lives on CDC’s Active People, Healthy Nation at-a-glance page, last reviewed on 27 March 2026. So it is current.
We looked for the source three ways.
On the webpage itself, there is no footnote, no inline citation, no reference marker. The only sourcing line is a content attribution to CDC’s National Center for Chronic Disease Prevention and Health Promotion, which links to that center’s homepage.
The page carries a Sources control in the same toolbar as Print and Share. It points to an anchor on the page itself. No reference list appears anywhere in the page.
Then there is the PDF, offered as a download of the full file. It repeats the sentence word for word. It has no bibliography, no footnotes and no citations of any kind. And it carries two dates: NOVEMBER 2019 at the top, and a March 2026 line in the footer. So the webpage was reviewed in 2026 while the document behind it appears to date from 2019.
A second CDC page, on parks, recreation and green spaces, states a rounded version: less than half of people in the United States live within half a mile of a park. Last reviewed 31 January 2025. Also uncited.
None of this makes the figure wrong. CDC is a serious agency and the number almost certainly comes from a real geospatial analysis. But a reader cannot check it, cannot date it, and cannot find out what counted as a park. When you quote it, quote it as what it is: a CDC figure, with CDC’s review date, and no published source.
Three federal distances for one idea
Here is where it gets interesting. Two different parts of the federal government measure park proximity, and they do not use the same yardstick. In fact there are three yardsticks.
CDC uses half a mile. That is the distance behind the 39 percent.
EPA’s EnviroAtlas, at national scale, uses 800 metres. The dataset is called public outdoor recreational area per capita within walking distance for the conterminous United States, published by EPA’s Office of Research and Development and last updated 21 February 2025. It measures how near public outdoor recreation areas are to people, and how much recreation space is available per person who can reach it. Critically, it measures along walkable routes, not as the crow flies. The catalog entry equates 800 metres to roughly half a mile or a 10-minute walk.
EnviroAtlas at community scale uses 500 metres from a park entrance. The community-level datasets, built for individual metro areas, show the block group population within and beyond an easy walking distance of 500 metres of a park entrance.
Now compare them. Five hundred metres is about 0.31 miles, materially stricter than half a mile, which is roughly 800 metres. Apply the community-scale threshold nationally and the share counted as having park access necessarily falls, because everyone living between a third of a mile and half a mile moves from inside the line to outside it.
The second difference matters more than people expect. Measuring from a park entrance is a different question from measuring to the park boundary. A 300-acre park with two gates serves a smaller walkable population than a 3-acre pocket park that opens onto the sidewalk on all four sides. And measuring along walkable routes rather than in a straight line changes who counts whenever an interstate, a rail corridor or a river sits between a house and the green space you can see from its window.
One more thing about EnviroAtlas. The national dataset publishes no national summary percentage. There is no EPA equivalent of CDC’s 39 percent. The data exists, mapped, downloadable. Nobody has reduced it to a headline. And the community-scale park access data was last updated on 3 February 2016, so it should not be described as current.
What happens when you ask people instead
Measuring from satellites and street networks is one approach. Asking Americans is another, and it produces different numbers.
A 2006 study in Pediatrics by Deborah Cohen and colleagues at the RAND Corporation, examining park proximity and physical activity in 1,556 sixth-grade girls, opens by stating that the United States already has an extensive park infrastructure, with 70 percent of adults saying they live within walking distance of a park or playground.
Seventy percent. Against CDC’s 39 percent.
Both numbers are defensible and they do not describe the same thing. CDC’s is a geographic calculation against a defined distance of half a mile, with an unpublished method and an unclear vintage. The 70 percent is self-report, offered as background rather than as a study finding, and it rests on the phrase walking distance, which nobody defined. People who would walk a mile without thinking about it and people who would not walk three blocks both answered that question. We are not going to resolve the gap, because it cannot be resolved. They measure different constructs.
A much more recent federal self-report study gives a third number and is more useful than either. Hatidza Zaganjor and colleagues at CDC published an analysis in Preventing Chronic Disease in 2025, drawing on the 2022 SummerStyles survey of 3,967 US adults. Asked what prevents them from regularly walking to places within a 10-minute walk of home, 79.0 percent named at least one reason. The most common was hot and humid conditions, at 36.0 percent. Second was that there are no places to walk to within 10 minutes of home, at 24.9 percent. A preference for driving came in at 22.1 percent and inconvenience at 21.5 percent.
Read 24.9 percent next to CDC’s 39 percent and you see the problem clearly. One in four adults says there are no places to walk to within ten minutes of home. CDC’s own park metric says six in ten have no park within half a mile. Those cannot both be measuring the same thing, and they are not: one asks about destinations in general, the other calculates distance to a specific land use. Neither is wrong. Both get quoted as though they settle the same argument.
The most detailed national map is run by a private nonprofit
If you want to know about park access where you live, the best mapped resource in the country is not federal. It is ParkServe, built by the Trust for Public Land.
The scale is impressive. ParkServe maintains an inventory of about 150,000 parks across every urban area in the United States, including Puerto Rico. Its method is published: it uses a 10-minute walk, estimated at half a mile, as the proxy for close-to-home parks, and builds a walkable service area outward from each park’s public access points using a commercial street-network dataset. Highways, rail lines and rivers without bridges are accounted for rather than ignored.
The companion ParkScore index rates the 100 most populous US cities across five categories, acreage, investment, amenities, access and park space equity, each worth up to 100 points, with the 500-point total normalized to a score out of 100. Access points are awarded on the share of the population living within a 10-minute, half-mile walk of a public park.
That is a more transparent method than CDC publishes. So why treat the numbers carefully?
Three reasons, none of which makes the organization wrong.
First, the denominator. ParkServe covers nearly 13,000 cities, towns and villages, which the organization says represent about 75 percent of the US population. Its headline claim, that over 100 million people do not have access to a park within a 10-minute walk of home, is drawn from that universe. It is not national the way a reader assumes a national statistic is national.
Second, the claims shift. On a separate campaign page, the organization states that 1 in 3 people in the United States, including 28 million children, still do not have a quality park within a 10-minute walk. That page gives no methodology and no source. And the word quality does real work there. A count of people near any park and a count of people near a good park are different counts, and the campaign page does not say how quality was judged.
Third, the organization describes itself as a national nonprofit that creates parks and protects land for people, and states that it is an IRS-approved 501(c)(3). It builds and funds parks. A larger gap number supports that mission. That is not an accusation of bad faith. It is the ordinary reason to prefer a published method, which the organization does provide for ParkServe and does not provide for the 1-in-3 figure.
Park access belongs to the category this library calls undefined. No federal rule fixes its meaning. Every number you will ever see is one organization’s measurement choice.
Being near a park does not mean using one
The quiet problem with all of this is that distance turns out to be a weak predictor of what people do.
The sharpest evidence comes from a study most people get backwards. Cohen and colleagues published an observational study in Preventive Medicine in 2010 covering 30 parks in a Southern California metropolitan area, with 51 park directors surveyed and 4,257 park users and local residents interviewed between 2006 and 2008.
Four things turned out not to predict park use: neighborhood population density, neighborhood poverty levels, the presence of a park advisory board, and perceptions of park safety.
That last one is worth sitting with. Cohen and colleagues wrote that while perceptions of low safety have been considered a barrier, “perceptions of high safety do not appear to facilitate park use.” A park people feel safe in is not thereby a park people go to. The strongest correlates in that study were park size and the number of organized activities happening there, a finding our article on what makes a park get used covers in detail.
Be careful what you take from that. It does not mean safety is irrelevant to anybody. The 2025 CDC survey found 14.5 percent of adults named feeling unsafe, for any reason, as something that stops them walking to nearby places. It means the measured association between how safe people say a park feels and how many people are counted in it was absent in that sample. Those are different claims.
Distance behaves the same way. Billie Giles-Corti and colleagues audited 516 public open spaces in Perth, Australia, and interviewed 1,803 adults, reported in the American Journal of Preventive Medicine in 2005. Their three nested models are the useful part: the likelihood of using open space rose with access in all of them, but the effect was larger in the model adjusting for distance, attractiveness and size together than in the model using distance alone. After adjustment, people with very good access to large, attractive open space were 50 percent more likely to achieve high levels of walking, odds ratio 1.50, 95 percent confidence interval 1.06 to 2.13.
Danish research points the other way at coarser distances. Two studies drew on the 2005 Danish National Health Interview Survey of 21,832 adults. Mette Toftager and colleagues, in the Journal of Physical Activity and Health in 2011, found that adults living more than 1 km from green space had lower odds of using it to exercise than those within 300 metres, odds ratio 0.71, and higher odds of obesity, odds ratio 1.36. Ulrika Stigsdotter and colleagues, in the Scandinavian Journal of Public Health in 2010, working with the 11,238 respondents who also returned the written questionnaire, reported that the same far group had 1.42 times the odds of experiencing stress. Both studies are entirely self-reported, including the distance measure, which is a known source of bias.
The honest synthesis: proximity shows up clearly at coarse contrasts, more than a kilometre against less than 300 metres, and fades against quality and programming at the fine contrasts that American park metrics use. The difference between 0.4 miles and 0.6 miles is where the national statistics live. It is not where the behavior changes.
The strongest federal statement is a finding of insufficient evidence
The Community Preventive Services Task Force reviewed 38 studies and issued a finding in July 2021.
Where park, trail and greenway infrastructure was combined with additional interventions, the Task Force recommends it. Across the 21 combined-intervention studies, moderate-to-vigorous physical activity rose 17 percent in seven studies, and use of the space rose 18.3 percent in nine.
Where infrastructure was built alone, with nothing else, the Task Force found insufficient evidence to determine whether it increases physical activity. That covered 17 of the 38 studies. Use went up after improvements, but the physical activity results did not point consistently in one direction.
Two dates matter. The literature search ended in July 2020. The pages carrying the finding were last updated on 31 December 2025. So the strongest federal evidence statement available on parks and physical activity rests on research published more than five years ago.
A peer-reviewed review reaches a similar place. Kathryn Derose, Deborah Cohen and colleagues reviewed 27 park-based intervention studies in Preventive Medicine in 2021, searching through September 2019. Fewer than half the place-based studies earned an average quality rating of high, and the authors’ own summary line is the one to keep: “The study of parks as sites for physical activity interventions is nascent.”
How to read any park-access number
When you see a figure for park access, these four questions sort it out in about a minute. They are our own, built from the discrepancies above.
- What distance? Half a mile, 800 metres, 500 metres and a 10-minute walk are four different lines, and the answer changes with each.
- Measured how? Straight-line distance counts people a highway cuts off. Network distance along walkable streets does not. Ask which one.
- Measured to what? To the park boundary, or to a park entrance? For large fenced parks these produce very different counts.
- What is the denominator, and when was the data collected? A figure covering 75 percent of the population is not national. A page reviewed in 2026 may be carrying an analysis from 2019.
If the publisher cannot answer question one, stop. If the publisher cannot answer any of the four, you are looking at a number that cannot be checked, which is a different thing from a number that is wrong.
What this is good for
The national percentage is the least useful number in this whole subject. Whether the right answer is 39 percent or 70 percent or something else entirely, it tells you nothing about your street.
What you can do is look up your own address in a tool that publishes its method. EnviroAtlas is free, federal and mapped, though the community-scale park data is nearly a decade old and the national walking-distance dataset publishes no summary figure. ParkServe is free, maps about 150,000 parks, and states its half-mile walkable-network method plainly, with the caveat that it is produced by an organization that also builds parks.
Then check what the measurement missed. Walk the route. See whether the half-mile line crosses a six-lane road with no signal, whether the nearest entrance is on the far side, whether the park is open when you would go. Every one of those is invisible to a national statistic and decisive for whether you use the place.
One personal note the statistics cannot capture. If what stops you walking for ten minutes is not the distance but your body, chest discomfort, unusual breathlessness, dizziness, or leg pain that shows up at a predictable distance and eases when you stop, raise it with a clinician rather than filing it under being out of shape. A limit that repeats at the same point every time is a different signal from general tiredness.
And if you are the one quoting a number, quote the threshold with it. Not 39 percent of Americans live near a park, but 39 percent live within half a mile, per CDC, which publishes no source. That sentence is longer. It is also the only one that survives someone checking.
Sources
- Centers for Disease Control and Prevention. “Active People, Healthy Nation: At a Glance (last reviewed 27 March 2026).” cdc.gov
- Centers for Disease Control and Prevention. “Active People, Healthy Nation At a Glance (PDF, dated NOVEMBER 2019 / DNPAO March 2026).” cdc.gov
- Centers for Disease Control and Prevention. “Parks, Recreation, and Green Spaces (last reviewed 31 January 2025).” cdc.gov
- US Environmental Protection Agency / Data.gov. “EnviroAtlas – Public outdoor recreational area (per capita) within walking distance for the conterminous United States.” catalog.data.gov
- US Environmental Protection Agency / Data.gov. “EnviroAtlas – New York, NY – Park Access by Block Group.” catalog.data.gov
- US Environmental Protection Agency. “EnviroAtlas.” epa.gov
- Community Preventive Services Task Force. “Physical Activity: Park, Trail, and Greenway Infrastructure Interventions When Combined With Additional Interventions.” thecommunityguide.org
- Community Preventive Services Task Force. “Physical Activity: Park, Trail, and Greenway Infrastructure Interventions Implemented Alone.” thecommunityguide.org
- Trust for Public Land. “About ParkServe.” tpl.org
- Trust for Public Land. “About the ParkScore Index.” tpl.org
- Trust for Public Land. “10-Minute Walk.” tpl.org
- PubMed. “Zaganjor H, et al. "Self-Reported Reasons Preventing US Adults From Walking to Places Within 10 Minutes of Home." Prev Chronic Dis, 2025. DOI: 10.5888/pcd22.240394.” doi.org
- PubMed. “Cohen DA, et al. "Parks and physical activity: why are some parks used more than others?" Prev Med, 2010;50 Suppl 1:S9-12. DOI: 10.1016/j.ypmed.2009.08.020.” doi.org
- PubMed. “Cohen DA, et al. "Public parks and physical activity among adolescent girls." Pediatrics, 2006. DOI: 10.1542/peds.2006-1226.” doi.org
- PubMed. “Giles-Corti B, et al. "Increasing walking: how important is distance to, attractiveness, and size of public open space?" Am J Prev Med, 2005. DOI: 10.1016/j.amepre.2004.10.018.” doi.org
- PubMed. “Toftager M, et al. "Distance to green space and physical activity: a Danish national representative survey." J Phys Act Health, 2011. DOI: 10.1123/jpah.8.6.741.” doi.org
- PubMed. “Stigsdotter UK, et al. "Health promoting outdoor environments." Scand J Public Health, 2010. DOI: 10.1177/1403494810367468.” doi.org
- PubMed. “Derose KP, et al. "Effects of park-based interventions on health-related outcomes: A systematic review." Prev Med, 2021. DOI: 10.1016/j.ypmed.2021.106528.” doi.org