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Where are the national parks really crowded?

Where are America’s national parks really crowded? Not across the whole park: most visitors keep to the scenic roads, the short trails near them and the visitor centres. Here each of 25 parks has a visitor core drawn by one written rule, and visits are counted per km² of core as well as per km² of park, month by month since 2015.

Spread over the whole park, Zion’s 4,984,525 visits in 2025 come to 22.7 a km² a day. In its visitor core, 5.6% of the park, it is 405 a km² a day, and 564 in May 2025: the busiest core of the parks whose roads the Park Service maps.

A count per park, with no place in it

The Park Service publishes every park’s recreation visits, month by month since 1979. A count has no place: it cannot say whether a park’s visitors spread across 9,000 km² or queue along one canyon road. The park boundary gives an area, and dividing by it makes Yellowstone look empty. The roads, trails and visitor facilities are in the Park Service’s own maps. Drawn into one core per park and keyed to the count by the park’s unit code, they show where the crowds are.

The map

Zoomed out, each park is a dot in its core’s colour: visits per km² of core a day in the month on the slider. Press Play to watch the seasons move across the country, 132 months from January 2015. Zoom in, or pick a park, to see its core over the aerial photo inside the dashed park boundary. Hover over a park, or tap it on a phone, for its numbers.

Crowded where people go

Ranked by the whole park, Zion is 4th of the 21 parks whose roads the Park Service maps; ranked by its core it is first. Grand Canyon climbs from 14th to 8th: its 4,869 km² are mostly canyon no road reaches, and its core is 2.14% of it. Shenandoah falls from 9th to 17th: Skyline Drive runs the length of a narrow park, so much of it is core.

The seasons

A core’s crowd follows the calendar. In the average month of 2015 to 2024, Yellowstone’s core took 97 visits a km² a day in Jul and 2 in Nov, when most of its roads are closed. Acadia went from 6 in Jan to 320 in Aug. Zion never empties: 108 in Jan, 541 in Jun.

How it was made in Plotlay

1. The rule, written down first. A park’s visitor core is 250 m either side of its paved park roads, 100 m either side of trails within 2 km of those roads, a 200 m disc round each visitor facility (visitor centres, lodging, campgrounds, trailheads, overlooks, parking) and each parking lot grown by 50 m, clipped to the park. The same rule for every park, from the Park Service’s own maps, measured in equal-area projections.
2. A map project on the USGS National Map aerial photo (public domain), and two data layers.
3. Parks and Cores: Take all. The 25 boundaries, then the 25 cores, each in one step, keyed by the park’s unit code (ZION, YELL...).
4. Link by key each park’s 2025 summary, then 3,300 park months as a time axis: visits, and visits per km² a day of the park and of the core.
5. Colour the cores by visits per km² of core a day and the parks, lighter, by visits per km² of park, for the month on the slider.
6. Charts and map pictures in the Analysis workspace, exported as PNG; both layers exported as GeoJSON, TopoJSON and CSV with WKT.

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Python

A narrated Jupyter notebook reads the tables and shapes, recomputes every number on this page, and maps Zion’s core.

Download the notebook (with its outputs) and the data. Both are also in the repository on GitHub.

Read it carefully

• Counting methods vary by park. The Park Service counts with traffic counters and per-vehicle multipliers set in each park’s counting instructions, changed over the years. A jump between years can be a new method.
• The cores are drawn estimates, from one written rule over the Park Service’s mapped roads, trails and facilities, not measured visitor footprints. Denali’s core counts its whole park road, though private cars stop at mile 15. With 500 m road buffers instead of 250 m, the five busiest cores are the same parks in the same order.
• Four parks have no NPS road data (Cuyahoga Valley, Hot Springs, Gateway Arch, New River Gorge). Their cores follow every public street (Census TIGER), so they read larger and emptier; they are in the map and the data but left out of the rankings.
• Visits are not unique people. Someone who leaves and comes back counts again; a week’s stay counts once.
• A day is an average. A month’s visits over its days; a summer Saturday is several times busier. Closures show: April 2020, Death Valley after the floods of September 2023, and the shutdown of October and November 2025, whose figures may still change.

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