MileCheckDoes my state DOT publish mile marker data?
Almost every state publishes something, but not the same thing. Some give the surveyed position of each sign. Some give only a route line with mileage, so the points have to be placed at each mile. A few cover only interstates.
What we found across 50 states
Building the MileCheck dataset, 24 states published their mile markers as points the state describes as sign locations. 19 published route lines, and we placed markers along them at each mile. 7 had sign points on some roads and route lines on the rest. Either way, positions are approximate.
Examples
- Pennsylvania's public mile marker points cover interstates only.
- For Maine, Vermont and New York, MileCheck builds the points from the state's route lines with mileage.
- California uses county-based postmiles. Georgia numbers state routes by county.
How to find yours
Search the state DOT's open data or GIS portal for "milepost", "mile marker", "reference post" or "LRS". Our data sources page lists the agency and feed we use for each state.
Mile marker data for all 50 states
396,842 marker positions as CSV and GeoJSON, one layout for every state, with a list of what changed in each release. Download the Utah sample with no form.
Questions, answered
Why would a state only publish route lines?
Many DOTs manage roads with a linear referencing system, where a location is a route plus a measure. The signs are physical assets that may be tracked in a different system, or not published.
Is there one file for every state?
Not from the government. The MileCheck milepost dataset combines all 50 states into one layout.