What ships inside the app

Most apps that know where the roads are ask a server. Interstate Tracker carries the roads with it.

The whole signed Interstate network is built ahead of time and bundled into the app: 226 routes, 49,106 miles by route measure, every state with Interstate mileage except Alaska, plus DC. Of the 226, 72 are the one- and two-digit primary routes and 154 are the three-digit spurs and loops that hang off them. The longest single route is I-90, at ≈ 3,086 miles by route measure.

The figures are counted from the network build the app ships, made on September 12, 2026 from the 2025 Census TIGER/Line geometry. If they change here, the map changed.

Editor’s note, September 13, 2026: the map changed, so the figures above did too — the counts read 225 and 153 when this was published, from the network build of July 6, 2026. Route measure is the length of the geometry; the number the app counts against is 48,964 reference miles, exit to exit.

Why carry it

Because the drives worth recording are the ones that leave. West Texas, or I-70 across eastern Utah: an app that phones home to match your position stops working there, and those are the places you most want the credit.

Matching on the device means recording never depends on being online. The build in testing today has no permission to use the network at all.

Editor’s note, September 13, 2026: the app signs in and syncs finished trips now, so it does declare the internet permission. Signing in is optional, and a phone that never signs in never opens a socket.

Where the geometry comes from

Three sources, and their licenses are what make bundling them possible:

• Census TIGER/Line for the road geometry and the state boundaries.
• The FHWA route log for which designations exist and where they run.
• OpenStreetMap for the exits — the points where a numbered interchange leaves the road (© OpenStreetMap contributors, ODbL).

The first two are public domain. The exits are what turn a road into the stretches the app credits: progress is counted from one exit to the next, so an exit in this app is a boundary on the centerline, not a ramp you have to drive.

None of this is a general road network, and that changes the matcher’s job. It has to decide which Interstate centerline a trace belongs to, and whether it belongs to one at all — not which of every road in America is nearest. A frontage road a hundred feet from the highway isn’t in the bundled network, and a GPS trace on one still looks a great deal like a trace on the highway.

What it costs

Carrying the network makes the app a bigger download. In exchange it works everywhere, and it never has to send your position anywhere.

If you want the longer version of how a trace becomes coverage, it’s in how it works.