Support & Contact

Have a question, found a bug, or have a feature request? We'd love to hear from you.

Report a Bug or Request Data

Found a bug, incorrect milepost data, or want to request a new state or feature? Submit an issue on GitHub so we can track and resolve it:

github.com/flintknap/SnagMP-Website/issues

General Inquiries

For anything else, email us at:

info@snagmp.com

Frequently Asked Questions — SnagMP Maps (Web App)

Which states are supported?

41 states are currently supported. Each state uses its DOT's official Linear Referencing System for milepost data. Additional states are being added regularly.

How accurate is the milepost data?

Milepost data comes directly from each state DOT's official Linear Referencing System (LRS), providing sub-foot accuracy for milepost location.

How accurate is the elevation data?

Cross-sections use USGS 3DEP LiDAR data (1-meter resolution) via the National Map. This is suitable for planning and reconnaissance purposes but is not survey-grade.

How do I look up a milepost?

Click anywhere on the map to get the nearest route, milepost, direction, and elevation. Or use the Search Milepost button to enter a route and milepost directly.

What is Analyze Location?

Analyze Location generates a LiDAR cross-section, fetches parcel boundaries and right-of-way widths (30 states), and displays site data including speed limit, functional class, AADT, and more.

Why do I see "MP (Back)" on some results?

Some highway segments have "equation points" where the milepost numbering resets or overlaps due to historical realignments. "Back" indicates the segment before the equation point, while "Ahead" indicates after.

Does SnagMP Maps work on mobile?

Yes. SnagMP Maps works on any device with a modern web browser. For GPS-based fieldwork with offline support, see SnagMP Field.

Is SnagMP Maps free?

SnagMP Maps is currently available at no cost. Core milepost lookup and search will remain free permanently.

Frequently Asked Questions — SnagMP Field

What is SnagMP Field?

SnagMP Field is a GPS-based milepost locator built for highway fieldwork. It runs as a Progressive Web App (PWA) on your phone and works completely offline after a one-time data download.

How do I install SnagMP Field?

Visit the Field app URL in Chrome or Safari on your phone and tap "Add to Home Screen." It installs like a regular app — no app store needed. Then open Settings within the app and download your state's route data.

Does Field work without cell service?

Yes. After downloading the route data for your state (a one-time download of 6–31 MB depending on state), SnagMP Field works entirely offline using your phone's GPS.

What is Station (STA) Mode?

Station Mode lets you set a reference point at your current milepost and then tracks your station value in real time as you walk or drive. This is useful for tying project stationing to mileposts in the field.

Is SnagMP Field free?

SnagMP Field is currently available at no cost.