Download Contour Lines as GeoJSON for QGIS and ArcGIS

Generate contour lines for anywhere in Oregon from USGS 3DEP lidar elevation data and download them as GeoJSON: WGS84 lines with the elevation in feet, ready for QGIS, ArcGIS, web maps and scripts.

What is GeoJSON?

GeoJSON is an open standard for geographic data written as plain JSON text. It is the native language of web maps and is read by every modern GIS. Because it is text, you can open it in any editor and see exactly what is inside.

For contours, each line is a feature with a geometry (the line itself) and properties (its elevation). That makes it easy to style contours by height, label them, filter them or feed them into an analysis.

What you get in the file

• One feature per elevation: every contour level is a MultiLineString feature holding all the lines at that height.
• Elevation in feet: elevation_ft and elevation (feet) on every feature, above NAVD 88, with elevation_m (meters) alongside.
• WGS84: longitude and latitude, as the GeoJSON standard requires.
• Attribution inside the file: top-level attribution and license members name the USGS 3D Elevation Program, so the source travels with the data. GIS readers ignore them.

Software that reads GeoJSON

Desktop GIS

• QGIS: free and open source; opens GeoJSON natively.
• ArcGIS Pro: converts GeoJSON with JSON To Features.
• ArcGIS Online: adds GeoJSON as a layer.
• Global Mapper: reads and converts GeoJSON.

Web mapping

• Leaflet: L.geoJSON() draws the contours in a few lines of code.
• MapLibre GL JS and Mapbox GL JS: add the file as a GeoJSON source and style lines by elevation_ft.
• OpenLayers: reads GeoJSON with its built-in format class.

Data processing

• Python: GeoPandas and Shapely read the file directly.
• GDAL/OGR: ogr2ogr converts it to GeoPackage, Shapefile or a database table.
• PostGIS: import with ogr2ogr for spatial queries.

How to download contour lines as GeoJSON

1. Open the map: go to Download Data and search for a place, address or peak.
2. Select the area: draw a rectangle, or click a taxlot to select the rectangle around it. The area can be up to 7.5 miles per side.
3. Choose the interval in feet (1, 2, 5, 10, 20, 40, 100, 200, 500 ft):
   • 1–5 ft: lots, drainage design and gentle ground such as the Willamette Valley floor
   • 10–20 ft: hillside parcels, trails and general mapping
   • 40 ft and up: big mountain areas, from the Columbia Gorge to the Wallowas
4. Choose GeoJSON among the contour formats.
5. Download: the contours are free to view on the map; the file needs a pass.
6. Open it: drag the file into QGIS, add it to ArcGIS, or load it in your web map.

The Contour Lines tool can also save the contours it draws on the map as GeoJSON or KML, clipped to the taxlot when you have selected one.

Using GeoJSON contours in QGIS

1. Add the layer: drag the .geojson file onto the QGIS map canvas.
2. Style by elevation: use a graduated renderer on elevation_ft for a color ramp.
3. Index contours: with a rule-based renderer, draw every fifth line heavier, for example "elevation_ft" % 50 = 0 at a 10 ft interval.
4. Label: label with elevation_ft and place labels along the line.
5. Combine: add a hillshade, taxlots or trails for context.
6. Save: export to GeoPackage if you want to keep styles and other layers together.

Common uses

Web maps

Developers add contours to Leaflet or MapLibre maps for trail sites, real estate listings and outdoor apps. A single GeoJSON file needs no tile server.

GIS analysis

Analysts combine contours with taxlots, streams and zoning to understand terrain constraints, or use them to check how a proposed road or building pad fits the ground.

Trail planning

Trail builders and land managers use contours to lay out routes at a steady grade, from forest roads in the Coast Range to new singletrack near Bend. Pair them with an elevation profile for the climb.

Environmental and watershed work

Contours help with drainage patterns, wetland edges and restoration plans. For flow paths, the Water & Drainage tool traces them directly.

Planning and development

Planners use contours to screen slopes and view corridors before a site visit. For permits, the county planning department decides what elevation information it needs; check with your county.

Tips

Keep files small

The finer the interval and the larger the area, the bigger the file. For web maps, choose the coarsest interval that still shows what you need, or simplify the lines in QGIS. Output resolution scales with the size of the area you select. Exports are capped at 1,024 pixels on the longest side, with a floor of 3.3 ft per pixel — so a 900 ft building site is delivered at the full lidar detail, while a block 7.5 miles on a side is resampled to roughly 39 ft per pixel. Select a smaller area when you need fine detail.

Mind the coordinate system

The file is WGS84. QGIS and ArcGIS reproject on the fly; for measuring lengths or areas, save a copy in Oregon Statewide Lambert, feet (EPSG:2992) or another projected system first.

Combine with other data

Contours read best over a hillshade and next to roads, streams and property lines. The DEM download guide shows how to get the elevation model itself as a GeoTIFF (above NAVD 88; values in the file are in meters, as USGS publishes them).

Script it

Because the file is plain JSON, a few lines of Python or JavaScript can filter levels, compute lengths or convert it to another format.

GeoJSON or another format?

GeoJSON or Shapefile

A Shapefile is a set of files zipped together and suits older ArcGIS workflows. GeoJSON is a single text file, handles long field names and is what web maps expect.

GeoJSON or DXF

For CAD, choose DXF: 3D polylines in Oregon Statewide Lambert, feet (EPSG:2992), with a layer per elevation. GeoJSON is the better fit for GIS and the web.

GeoJSON or KML

KML is made for Google Earth, with colors and height labels built in. GeoJSON is better for analysis and custom web maps.

About the data

Ground elevations on this site come from the USGS 3D Elevation Program (3DEP) seamless bare-earth model: 3.3 ft per pixel where lidar has been flown and about 33 ft per pixel elsewhere, with elevations above NAVD 88. The data is in the public domain. Most of Oregon’s lidar was flown through the Oregon Lidar Consortium, run by DOGAMI, the Oregon Department of Geology and Mineral Industries. DOGAMI reports about 99% of Oregon covered by at least one lidar project. See lidar coverage in Oregon for the project behind your area. More from the USGS 3D Elevation Program and DOGAMI’s lidar program.

Accuracy is inherited from the USGS 3DEP source and the lidar project behind it, not asserted by this tool. Where lidar exists, at 3.3 ft per pixel, vertical accuracy is that of the project: individual Oregon Lidar Consortium projects report vendor RMSE of a few inches or less in DOGAMI’s project records; for example, Metro 2014 reports about a tenth of a foot. Outside the lidar work units the seamless DEM is about 33 ft per pixel and far coarser. Every download states what share of its area fell outside the lidar work units. Values are bare-earth elevations above NAVD 88 from a digital elevation model — they exclude buildings and tree canopy and are not a substitute for a surveyed elevation where a legal or engineering decision depends on it.

Frequently asked questions

Other formats

• Contours as DXF – for AutoCAD and Civil 3D
• Contours as KML – for Google Earth
• Contours as PDF – for printing
• Contours as SVG – for design and laser cutting
• Contour lines for Oregon – overview of every format