Steep grades map

Long climbs and descents on interstates and US routes, by route and mile marker. Each line is a calculated stretch of two miles or more that averages a 4% grade or steeper. These are terrain-based estimates over whole miles. Short sections of road can be steeper than the average shown. Follow the grade signs on the road.

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State

4 to 5%5 to 6%6% and up

Pick a state or zoom in to load cameras, chain rules and winter road reports.

Turn layers on and off with the stack button at the bottom right of the map.

Steep grades in view

See the mile marker as you drive.

MileCheck shows your nearest mile marker in real time, so you can compare where you are with the mile markers on this map. Works offline in all 50 states.

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How this was built: we took the elevation at each mile marker on US interstates and US routes in the MileCheck milepost data and calculated the elevation change between consecutive markers. Distance between two markers is estimated as one mile, or the straight-line distance when that is longer. We don't have measured road distance. Elevation comes from Mapzen Terrain Tiles hosted on AWS, which use USGS 3DEP, SRTM and other terrain sources. A stretch appears when two or more miles in a row have a calculated average grade of 4% or more in the same direction. That cutoff is our own choice, not a DOT threshold. These are terrain-based estimates over whole miles, not surveyed roadway grades. A single steep mile does not qualify by itself. Single miles calculated over 12% on interstates or 15% on US routes are left out, because terrain above a tunnel can read as a false grade. That can also leave out a few real steep miles. California uses county-based postmiles on many routes, so California coverage is incomplete. The camera, chain rule and winter report layers are live from state DOT feeds and refresh every 5 minutes. Cameras show when they sit within a mile of a stretch. This is not a DOT grade list. Road signs are the source to follow while driving. United States 3DEP (formerly NED) and global GMTED2010 and SRTM terrain data courtesy of the U.S. Geological Survey. Built October 3, 2026. See also steep grade signs explained, runaway truck ramps and the chain control map.